Because it's decreasing, you use the formula (1-x/100)y with x the percentage decreased which is here 40, and y the number decreased which is here 90 So we get (1-40/100) * 90 (100/100 - 40/100) * 90 60/100 * 90 5400/100 54 So 90 decreased by 40% is 54 Hope this Helps :)
