The sum of the present ages of two persons is seven times that of the difference between their ages. After 5 years, the sum of their ages will become nine times that of the difference. What is the present age of the elder person?

Sum of their present ages is 7 times the difference.

Sum of their ages after 5 years is 9 times the difference.

Therefore, 2 times difference $$=10$$ (Substracting the ages of 5years later from present age)

or, difference of their ages $$=5$$

Sum of their ages at present $$=7\times5 =35$$

Since there is only 5 years difference between them, present age of the elder person

$$=5+\frac{35−5}{2}=20$$

Option D is correct.