Question

What is a common denominator for 1/7 and 1/3? a 18 b 21 c 3 d 4

Answer 1

Answer:

B. 21

Step-by-step explanation:

The fractions are there to just make the problem seem complicated, but just rewrite it without the fractions.

"What is a common multiple for 7 and 3?"

In this problem it's easy, all you have to do is guess and check.

A: A doesn't work. 7 is not a factor of 18.

B: B works! Both 3 and 7 are factors of 21.

C: C doesn't work. 7 is not a factor of 3.

D: D doesn't work. Neither are a factor of 4.

They only leave us with one solution, B.