Answer:
 cups of raisins are in each serving
 cups of raisins are in each serving
Explanation:
Unit rate defined as the rates are expressed as a quantity as 1 such as 2 meter per seconds or 4 miles per hour.
As per the statement:
The bake star bakery uses 2 1/4 cups of raisins to make 4 servings of trail mix. 
⇒Cup of raisins = 
 and number of serving = 4
 and number of serving = 4
We have to find the cups of raisins are in each serving
Then by definition of unit rate we have;
 cups of raisins
 cups of raisins
therefore, 
 cups of raisins are in each serving
 cups of raisins are in each serving