Theory➡ Product of two numbers = Product of their LCM and HCF
The highest common factor(HCF) and the least common multiple(LCM) of two positive integers are 7 and 140HCF = 7, LCM = 140 = 7 * 2 * 2* 5
The numbers are between 20 and 45 and we need to find the sum of both the numbers.Now, we can start taking numbers such that the two numbers are a multiple of the HCF, which is 7, and their LCM = 140
1. We can take one number as 7*1, and other as 140 to have HCF = 7 and LCM=140, but the two numbers won't be between 20 and 45 then => NOT POSSIBLE
2. We can take one number as 7*2, and other as 140 to have HCF = 7 and LCM=140, but the two numbers won't be between 20 and 45 then => NOT POSSIBLE
3. We can take one number as 7*2*2, and other as 7*5 to have HCF = 7 and LCM=140, making the two numbers as 28 and 35. Both the numbers are within 20 and 45 => POSSIBLE
Sum of the numbers = 28 + 35 = 63
So,
Answer will be C.
Hope it helps!
Watch the following video to Learn the Basics of LCM and GCD