If Jack is 14 years older than Bill, in 10 years time Jack is twice as old as Bill. How old will jack be in 5 year time?
A. 9 B. 19 C. 21 D. 23
Correct Answer: D
Explanation
\(J = Jack , B =\) Bill \(J = B +14 \ldots \ldots \ldots \ldots(1)\) In 10 years time, \(J +10=2( B +10)\) \(J +10=2 B +20\) \(J -2 B =20-10\) \(J -2 B =10 \ldots \ldots \ldots(2)\) Put eqn \((1)\) into eqn........ (2) \(B +14-2 B =10\) \(14- B =10\) \(14-10= B\) Put \(B =4\) into eqn (1) \(J =4+14=18\) In 5 years time, Jack will be \(J +5=18+5=23\) years