 ' - ';
	else
		text += ' + ';
	text += Math.abs(b).toFixed(2);
	text += 'x';
	if(c < 0)
		text += ' - ';
	else
		text += ' + ';
	text += Math.abs(c).toFixed(2);
	return text;
}

function pretty_print_ab(a, b) {
	var text = '';
	if(a < 0)
		text += '-';
	text += Math.abs(a).toFixed(2);
	text += 'x';
	if(b < 0)
		text += ' - ';
	else
		text += ' + ';
	text += Math.abs(b).toFixed(2);
	return text;
}

function show(n) {
	document.getElementById("shown_" + n).style.display = "none";
	document.getElementById("hi