Twenty cookies need 1/4 cups of sugar. How much sugar is needed for 3 dozen?
note: 1 dozen = 12 cookies,,
thus 3 dozen = 3*12 = 36 cookies
let x = cups of sugar needed
we use ratio and proportion:
20 : (1/4) = 36 : x
we can rewrite this into fraction form:
20/(1/4) = 36/x
we then cross multiply,,
20*x = (1/4)*36
20x = 9
x = 9/20 cups
hope this helps~ :)