Charlie sold 100 tickets for his show. An adult ticket costs £6.50 and a child ticket costs £2.50
Charlie’s ticket sales totalled £410

a) how many adult tickets did he sell?
b) how many child tickets did he sell?

Use pythagorean’s theorem and find the missing side lengths of the two smaller triangles and add them together
13^2 - 12^2 = 5
15^2 - 12^2 = 9
5+9 = 14
14 is the length of each side of the square
14^2 + 14^2 = 19.8
19.8 is the diagonal length of the inside if the square

(less than or equal to)