Ninty three point six five I think
namely, what is 1/2 of 3/4, well, is just their product.

Wouldn't it be -1 (minus one)? 12 - 1 = 11 and 9 - 1 = 8.
100 * pi = pi * r^2
Pi cancels on both sides of the equation
So... 100= r^2
= radius is 10
Add the 28 and 42
then divide by 2
there should be 35 kids in group