There is a percent formula for all of these types of percent problems.
It is : is/of = %/100
224 is what % of 640 is = 224 of = 640 % = x now just sub 224/640 = x/100 cross multiply because this is a proportion (640)(x) = (224)(100) 640x = 22400 x = 22400/640 x = 35......so 224 is 35% of 640
