function mpg()
{
var uno = calc.uno.value;

//if('uno=='){alert('Odometer Reading must be entered.');
//calc.uno.focus();return false;}

var dos = calc.dos.value;

//if('dos=='){alert('Odometer Reading must be entered.');
//calc.dos.focus();return false;}


var gal = calc.gal.value;

//if('gal=='){alert('Gallons PUmped must be entered.');
//calc.gal.focus();return false;}




var od1 = uno;
var od2 = dos;
var g = gal;
var m = dos-uno;
var mpg2 = m/gal;

calc.m.value = m;
calc.mpg2.value = mpg2;

return false;

}