Answer 8+10 please. Very important that I get the right answer.

Me find the missing dimension of a triangle height: 7 in., area: 21^2

Giving 100 points asap bev has to cut her grandma's grass this weekend and wants to know exactly how much area she will be cutting. calculate the area of the polygon. be sure to show all your work and explain your answer.

The hawaiian alphabet has 12 letters. how many permutations are posible for each number of letters?