Question

Help pleasee

The ratio of cement to sand for mortar is 1:3.
If Sandy puts in 7 shovels of cement, how many shovels of sand should she put in?

Answer 1

Set this up as a proportion with cement on top and sand on bottom. Our proportions will look like this then:
`(1)/(3) = (7)/(x)`. Cross multiply to get x = 21. So 21 shovels of sand is needed.

Answer 2

Let x be the amount of cement and y be the amount of sand. If the ratio of cement to sand for mortar is 1:3, then
`(x)/(y) = (1)/(3)` and y=3x.

So, if Sandy puts in x=7 shovels of cement, then she puts
`y=3\cdot 7=21` shovels of sand.

Answer: 21 shovels of sand.