For this situation we will use a ratio to show how many free throws Erin will make. Using the ratio 7:10 represents that Erin will make 7 out of every 10 free throws. You want to know how many free throws she will make if she attempts 60 free throws.
Using ratios we will be able to find how many free throws she will make if she attempts 60.
7:10
14:20
21:30
28:40
35:50
42:60
Basically we kept multiply the right side of the ratio which is 10 by 2 until we were at 60 free throws.
Erin will make 42 free throws if she attempts 60 free throws.