Jones is now 7 times as old as White. If 10 years from now, Jones will be 3 times as old as White how old is Jones now?
A. 14
B. 21
C. 28
D. 35
E. 42
Let White be y years old. So, Jones is 7y years old now.
Ten years from now, White will be (y + 10) and Jones will be (7y + 10).
So, 7y + 10 = 3 (y + 10) = 3y + 30.
Thus, 4y = 20 or y = 5. White is 5 years old and Jones is 35 years old now.