Bunuel wrote:

Exactly 8 years ago, Jim’s son was twice as old as Jim’s daughter. If Jim’s son is now 5 years older than his daughter, how old is Jim’s daughter now?

(A) 5

(B) 10

(C) 13

(D) 16

(E) 18

\(? = D\)

\(\left\{ \begin{gathered}

\left( {S - 8} \right) = 2\left( {D - 8} \right) \hfill \\

S = D + 5 \hfill \\

\end{gathered} \right.\,\,\,\,\,\,\,\, \sim \,\,\,\,\,\,\,\left\{ \begin{gathered}

\left( {S - 8} \right) = 2\left( {D - 8} \right) \hfill \\

\left( {S - \underline 8 } \right) = \left( {D - \underline 8 } \right) + 5 \hfill \\

\end{gathered} \right.\,\,\,\,\,\,\,\,\mathop \Rightarrow \limits^{\left( {\, - \,} \right)} \,\,\,\,\,\,\,\,\left( {D - 8} \right) - 5 = 0\,\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,? = D = 13\)

The above follows the notations and rationale taught in the GMATH method.

_________________

Fabio Skilnik :: https://www.GMATH.net (Math for the GMAT)

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