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.
It is simply complement of 66% to 100%, and it is equal to 100% - 66% = 34%. It is your final answer.