So what there asking is what is the numerator after rewriting the fractions
They simply want you to write the equlivalent fractions so that the fractions can be added
1/4+1/6
=3/12+2/12
------>1/4 and 1/6 were multiplied by 3, to give a common denominator of 12
= 5/12
------> With the same denominator the numerators were added