He ratio table below describes the relationship between grapes and blueberries in a fruit salad. fruit salad grapes (cups) blueberries (cups) 2 0.5 6 1.5 20 5 24 6 mandie is making 15 cups of fruit salad. what ratio of grapes to blueberries should she use?

The first thing you should do for this case is to graph the data you have in the statement to see the relationship between grapes and blueberries.
 The function represented by the table is
 y = 0.25x
 Then, as Mandie is making 15 glasses of fruit salad, we have:
 y + x = 15
 We have two equations and two unknowns that we must solve.
 y = 0.25x
 y + x = 15
 Resolving
 For x: 
 0.25x + x = 15
 1.25x = 15
 x = 15 / 1.25 = 12
 For y: 
 y = 0.25x = 0.25 (12) = 3
 Answer
 The ratio of grapes to blueberries she should use is 12: 3