Question 1203980
.
Please help me solve this question. A boy is three times as old as his
sister. In 7 years he will be twice as old as his sister will be, find
their present ages.
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<pre>
Let x be the sister's age (in years).

Then the brother's age is 3x years, according to the problem.


In 7 years

    the sister      the brother
      2(x+7)      =   3x+7.


Simplify and find x

    2x + 14 = 3x + 7

    14 - 7 = 3x - 2x

      x   =    7.


Thus, the sister's current age  is 7 years; the brother's current age is 3*7 = 21 years.
</pre>

Solved.



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<H3>A post-solution note</H3>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1) &nbsp;&nbsp;when a male is &nbsp;21 &nbsp;year old, &nbsp;the word &nbsp;" a boy " &nbsp;is just not appropriate.



&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2) &nbsp;&nbsp;" solve the question " &nbsp;&nbsp;is the mafia's vocabulary.


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Normal people say &nbsp;" solve the problem ". &nbsp;&nbsp;Or &nbsp;" answer the question ".