If 22.5% is 18 how do i found out what 37.5% is

You can use proportions.

22.5/100 = 18/x
cross multiply:
100 x 18 = 1800
1800/22.5 = 80

so now you know 80 is the 100%.
then do:

37.5/100 = x/80
cross multiply:
37.5 x 80 = 3000
3000/100 = 30

37.5% = 30

Aquadratic function is one of the form f(x)=ax2 + bx + c l, where a,b, and c are numbers with are not equal to zero.

Ithink the answer is b.