Of the 105 students at mauna loa high school, 25 students take the bus to school, 21 are in an after-school tutorial, and 9 do both. how many students are neither in the tutorial nor ride the bus?

First find the number of students that either take the bus or are in tutorial:

25+21=46.

BUT, this double counts the students that do both, so we need subtract our double count:

46-9=37

37 students are in either group, therefore:

100-37=63 students are in neither.