Question

Bob the builder is making 480kg of concrete mix

concrete is made by mixing cement, sand and gravel in the ratio 1:3:4

Answer 1

60 kg of cement, 180 kg of sand and 240 kg of gravel

Explanation:

x : 3x : 4x

If you turn this into an equation, it becomes x + 3x + 4x = 480

8x = 480

x = 60

60 is the amount for the cement, for the sand and gravel multiply this answer by 3 and the other by 4, you should get 180 and 240

Sorry if this was not clear