The difference between the ages of two persons is 10 years. Fifteen years ago, the elder one was twice as old as the younger one. The present age of the elder person is
Choose the correct choice from the following answers
A) 25 years  B) 30 years  C) 35 years  D) 40 years  E) None
Sol.   Let their ages of x years and (x + 10) years respectively.   Then, (x + 10) - 15 = 2(x - 15)   ⇔ x - 5 = 2x - 30   ⇔ x = 25.   ∴ Present age of the elder person = (x + 10)   = 35 years.   Answer 35 years
<result>C</result>
The difference between the ages of two persons is 10 years. Fifteen years ago, the elder one was twice as old as the younger one. The present age of the elder person is