CAT 1995 — QA Question 31

Let one of the numbers be x. So the other number would be (x + 4).

According to the question, we have $\frac{1}{x}+\frac{1}{(x+4)}=$21 or x = 3.

Hint:

​​​​​​​Please note that the sum of reciprocals is basically $=\frac{(Sum of the int egers)}{(Product of the int egers)}$. 

So we have to find two integers whose sum is 10 and whose product is 21.

So x + (x + 4) = 10 or x = 3.

Hence, option (a).