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 answer:
A) 25 years
B) 35 years
C) 45 years
D) 55 years
E) 75 years
Solution   Let their ages be x year 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>B</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 :