Which expression shows 7+21 written as a product of two factors? (A)3(1+7)
(B)3(3+7)
(C)7(3+3)
(D)7(1+3)

for ex: the reciprocal of 3/4 is 4/3. it is the opposite.

reciprocal definition:

a mathematical expression or function so related to another that their product is one; the quantity obtained by dividing the number one by a given quantity.

answer is x<