Iforgot how to do it i wasn't at school for a couple of days

65% of students in your school participate in at least one after school activity. if there are 980 students in you school, how many do not participate in an after school activity?

I'm confused on this could anyone me and show me what i need to do to solve it.

The cross-sectional areas of a right triangular prism and a right cylinder are congruent. the right triangular prism has a height of 6 units, and the right cylinder has a height of 6 units. which conclusion can be made from the given information? the volume of the triangular prism is half the volume of the cylinder. the volume of the triangular prism is twice the volume of the cylinder. the volume of the triangular prism is equal to the volume of the cylinder. the volume of the triangular prism is not equal to the volume of the cylinder.