Step 1: \ \

Trail mix should contain five cups of peanuts for every two cups of raisins.

Set up a proportion. \ \

$\"\"$ .

Let $\"\"$ cups of raisins are needed to add 15 cups of peanuts.

$\"\"$

The proportions is $\"\"$ .

Step 2:

Find how many cups of raisins are needed to add 15 cups of peanuts.

\ \ Use proportions to find $\"\"$ .

$\"\"$

(c)

Therefore, 6 cups of raisins are needed to add 15 cups of peanuts.

Solution:

(a) The proportions is $\"\"$ .

(b) $\"\"$ .