Mary invests $10,000 at 4.5% interest a year, compounded quarterly.

(A)How much will she have after 20 years?

(B) If the interest were compound semi-monthly, how much more would Mary have after 20 years than compounded quarterly?

Equation

A=P[1+r/k]^kt

I got 24,472 after 20 years

But I dont know how to do the second part (B)