Answer
$15\,A's$, $21 \,B's$, $ 27\,C's$, $11\,D's$, $10\,F's$
Work Step by Step
We use the fractions to find the number of each category:
$\frac{18}{100}\times84\,A's=15\,A's$
$\frac{25}{100}\times84\,B's=21 \,B's$
$\frac{32}{100}\times84\,C's= 27\,C's$
$\frac{13}{100}\times84\,D's=11\,D's$
$\frac{12}{100}\times84\,F's=10\,F's$