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This problem is to be solved in two steps.
Step 1. Find the percentage of those who buys some of these two products.
It is 56% + 32% - 22% = 66%.
In this formula, it should be clear to you why I added 56% and 32%.
why I subtracted 22% ? - Because when I added, I counted TWICE those who buys both products.
Step 1 is completed.
STEP 2. Find the percentage of students that buy neither.
It is simply complement of 66% to 100%, and it is equal to
100% - 66% = 34%.
It is your final answer.
Solved.