Question

Two numbers are in the ratio 3: 7. Their L.C.M. is 126. Find the sum of the numbers.

• A. 60
• B. 90
• C. 64
• D. 69

Answer 1

Answer:

A. 60

Let the numbers be (3x) and (7x).

LCM of the numbers

Since 3 and 7 are co-prime:
$\text{LCM}(3x, 7x) = 21x$
Given:
$21x = 126 \Rightarrow x = 6$
Find the numbers

$3x = 18,\quad 7x = 42$
Sum

18 + 42 = 60