Question

To make butter biscuits we need 3/4 kg of sugar for every 2kg butter. If we use 15kg of sugar how much butter do we need

Answer 1

(3/4) / 2 = 15/x
(3/4)x = 30
x = 30(4/3) = 40

or

notice:
sugar : butter = 3/4 : 2
= 3 : 8

so 15:x = 3:8
3x=120
x=40