Question

40 nails hold 5 rafters. 96 nails hold r rafters.

Answer 1

5 times 96 divided by 40 gives you 12. 96 nails hold 12 rafters.

Answer 2

Ratio and proportion

nails:rafters=40:5
40/5=96/r
we can simplify left side
8/1=96/r
times both sides by r
8r=96
divide both sides by 8
r=12

12 rafters