Question

the difference between two sisters, ages is 5 year, of 10 year ago, if the elder one was twice as old as young one, find their present age.

Answer 1

Dear student,
$$\begin{gathered} Lettheageofyoungersisterbe\text{'}x\text{'} \\ thentheageofeldersisterbe(x+5) \\ 10yrsago, \\ (x+5)-10=2(x-10) \\ \Rightarrow x-5=2x-20 \\ \Rightarrow x-2x=-20+5 \\ \Rightarrow -x=-15 \\ \Rightarrow x=15 \\ thusthepresentageofyoungersisteris15yrs \\ andthepresentageofeldersisteris\left(15+5\right)=20yrs \end{gathered}$$
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