20% of 90 pizzas is 22.5 pizzas
And since you can’t just buy half a pizza it would have to be 23 pizzas :)
The answer for apex users are:
All of the radii of a circle are congruent
CPCTC
SSS triangle congruence postulate
The shaded areas add to 2/5 of the area of the circle, which is given by
A = πr²
Then the shaded area is ...
(2/5)A = (2/5)π(10 in)²
shaded area = 40π in²