Because 50% of something means half (because 100-50=50), he would have to make the number of girls and boys equal. Since there are 21 girls, he has to make it so there are also 21 boys.
So, if we know that 21-15=6, this means he would have to add 6 boys to the club if he wants the girls and boys equal.
ANSWER IS C because I looked it up
Polynomial is an expression consisting of variables and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables.
