I believe it's 10 because if there is a total of 32 that have bikes and 42 that have skateboards you just subtract 32 from 42 to get a total of 10. The table is a little messed up but I tried.
The answer is 30, because you have to retrieve the <u>totals</u>. The total amount of people who have bikes is 72. The total amount of people with skateboards is 42. Subtract 42 from 72. You get 30. Answer: 30.