Beth is making a fruit salad she adds 5 grapes for every 2 strawberries if she uses 20 strawberries how many grapes will she use

If Beth adds 5 grapes for every 2 strawberries, the ratio of grapes to strawberries is 5:2.

If she uses 20 strawberries, the number of grapes she will use can be calculated as 5/2 * 20 = <<5/2*20=50>>50 grapes. Answer: \boxed{50}.