<!-- hide from old browsers

if (window != top) top.location.href = location.href;

function windowMax(){
window.moveTo(0,0)
window.resizeTo(screen.width,screen.height)
}

//define a var to represent the URL for the requested image
imageURL1=""
imageURL2=""
imageURL3=""
imageURL4=""
imageURL5=""
imageURL6=""
imageURL7=""
imageURL8=""
imageURL9=""
imageURL10=""
imageURL11=""
imageURL12=""
imageNEW = new Image(40,20)
imageNEW2 = new Image(160,20)
imageNEW3 = new Image(480,20)
imageNEW4 = new Image(40,20)
imageNEW5 = new Image(440,20)
imageNEW6 = new Image(160,20)
imageNEW7 = new Image(40,20)
imageNEW8 = new Image(160,20)

//numbers within the parentheses refer to width and height, in that order

//load new images into memory
imageNEW.src ="images/X-pink.gif"
imageNEW2.src ="images/1x.gif";
imageNEW3.src ="images/3x.gif";
imageNEW4.src ="images/Rem-grn.gif";
imageNEW5.src ="images/890.gif";
imageNEW6.src ="images/grn-170.gif";
imageNEW7.src ="images/grn-X.gif";
imageNEW8.src ="images/170-blue.gif";

//define array syntax - where you will replace the image
/*the above number [1] refers to the second image tag in the HTML doc; zero counts first*/

function addLiq() {
	if (imageURL2=="images/X-pink.gif") {
	imageURL2="images/X-pink.gif";
	}
	else {
	imageURL2="images/X-pink.gif";
	}
document.images[2].src =imageURL2

	if (imageURL11=="images/X-pink.gif") {
	imageURL11="images/X-pink.gif";
	}
	else {
	imageURL11="images/X-pink.gif";
	}
document.images[11].src =imageURL11
}

function resultVol() {

// ADD WATER
if (imageURL2=="images/X-pink.gif") {
	imageURL2="images/X-pink.gif";
	}
	else {
	imageURL2="images/X-pink.gif";
	}
document.images[2].src =imageURL2

	if (imageURL11=="images/X-pink.gif") {
	imageURL11="images/X-pink.gif";
	}
	else {
	imageURL11="images/X-pink.gif";
	}
document.images[11].src =imageURL11

// RESULTING VOLUMES
	if (imageURL3=="images/1x.gif") {
	imageURL3="images/1x.gif";
	}
	else {
	imageURL3="images/1x.gif";
	}
document.images[3].src =imageURL3

	if (imageURL12=="images/3x.gif") {
	imageURL12="images/3x.gif";
	}
	else {
	imageURL12="images/3x.gif";
	}
document.images[12].src =imageURL12
}

function superImpose() {

	if (imageURL3=="images/1x.gif") {
		

// SUPERIMPOSE SMALL TANK ONTO BIG TANK
		if (imageURL8=="images/890-grn.gif") {

			imageURL7="images/Rem-grn.gif";
			imageURL8="images/grn-170.gif";

			imageURL10="images/170-blue.gif";
			}

// ENSURE THAT NO IMAGE CHANGE IF CLICK AFTER "HELP ME!"
		
				else if (imageURL8=="images/170-blue.gif") {

					imageURL7="images/X-pink.gif";
					imageURL8="images/170-blue.gif";
					imageURL9="images/X-pink.gif";

					}

// ENSURE IMAGE CHANGE FOR "SUPERIMPOSE" WHEN IN RIGHT ORDER
		else   {
			imageURL6="images/grn-170.gif";
			imageURL7="images/Rem-grn.gif";
			imageURL8="images/grn-170.gif";
			imageURL9="images/grn-X.gif";
			imageURL10="images/170-blue.gif";
			}
	}

// ALERT THAT EARLIER BUTTONS MUST BE CLICKED
	else {
		imageURL6="images/grn-170.gif";
		imageURL7="images/grn-X.gif";
		imageURL8="images/890-grn.gif";
		imageURL9="images/grn-X.gif";
		imageURL10="images/grn-170.gif";
		alert("Please start by adding water.");
		}
document.images[6].src =imageURL6
document.images[7].src =imageURL7
document.images[8].src =imageURL8
document.images[9].src =imageURL9
document.images[10].src =imageURL10
}

function verifyInput() {

// VERIFY REMAINDER
	entry = document.form.remainder.value
	if (entry == 2) {
	window.alert("Correct! 2 times or 2 units of 170 litres + 2 units of X")
	}
	else {
	window.alert("Please try again.")
	}
}	

function showPic() {

// SHOW PICTURES

	if (imageURL10=="images/170-blue.gif") {
	imageURL6="images/170-blue.gif";
	imageURL7="images/X-pink.gif";
	imageURL8="images/170-blue.gif";
	imageURL9="images/X-pink.gif";
	}
	else {
	imageURL6="images/grn-170.gif";
	imageURL7="images/grn-X.gif";
	imageURL8="images/890-grn.gif";
	imageURL9="images/grn-X.gif";
	alert("Please superimpose the small tank onto the big tank.")
	}
document.images[6].src =imageURL6
document.images[7].src =imageURL7
document.images[8].src =imageURL8
document.images[9].src =imageURL9
}

function verifyAnswer() {

// VERIFY ANSWER
	entry = document.form.answer.value
	if (entry == 190) {
	window.alert("Fantastic! 190 litres is the correct answer!")
	}
	else {
	window.alert("Please try again.")
	}
}	

function help() {

// HELP IN FINAL SOLUTION

	if (imageURL6=="images/170-blue.gif") {
	imageURL4="images/890.gif";
	alert("Draw a line to represent the original 890 litres.")
	}
	else {
	imageURL4="images/pixel.gif";
	alert("Please start by adding water; if you had done that then click on the Help Me! button.")
	}
document.images[4].src =imageURL4
}

function tanksoln(){
  mywin = window.open("tanksoln.htm","tanky","toolbar=no,menubar=no,location=no,scrollbars=yes,resize=yes,resizable=yes,width=630,height=430,left=0,top=0,statusbar=no")
 }
// end hiding -->