STEP 1:
Find total number of cups of all ingredients
= 3 1/2 cups + 1 1/2 cups
= 5 cups
STEP 2:
Divide 5 cups by the portion size per bag
= 5 ÷ 1/4
to divide fractions, multiply by the reciprocal/inverse of 1/4
= 5 * 4/1
= 20 bags
ANSWER: 20 bags
Hope this helps! :)