Question

Which of the following is a multiple of both 5 and 15?

• A. 35
• B. 55
• C. 45
• D. 20

Answer 1

The correct option is C 45

$45=5\times 9$
$45=15\times 3$

35, 55 and 20 are multiples of 5, but not of 15 and therefore, are not common multiples of 5 and 15.

Hence, 45 is a common multiple of 15 and 5.