Paul uses 2 and 1/4 cups of raisins to make 4 servings of trail mix. how many cups raisins are in each serving?

There are 9/16 cups of raisins in each servings

When dividing or multiplying you change the mix number into a improper fraction.
2 and 1/4 --> 9/4

Then you divide it by 4 but before that rewrite 4 as and improper fraction
4 --> 4/1

And the equation looks something like this
9/4 divide by 4/1

And you keep the 9/4 and change the division sign to a multiplication sign and lastly change the 4/1 to 1/4 and cross multiply