Question

Sam used cement and sand to prepare a mixture. The ratio of the number of pails of cement used to the number of pails of sand used was 1:2. Sam then added 8 more pails of cement and the ratio became 5:2.
A.) How many pails of cement was used at first?
B.) How many pails of sand was used?

Answer 1

original amount of cement = x
original amount of sand = 2x

new amount of cement = x + 8
new amount of sand = 2x

(x+8)/(2x) = 5/2
cross-multiply
10x = 2x + 16
8x = 16
x = 2

A) original amount of cement = 2 pails
B) original amount of sand = 4

check:
new amount of cement = 2+8=10
new amount of sand = 4

10: 4 = 5:2