<PRE><B>Question 1152522</B>
&lt;br&gt;
The solution by the other tutor is fine; and of course there are many other ways to solve the problem.&lt;br&gt;
I always prefer to set a problem up using only one variable if possible; so here is what I would do.&lt;br&gt;
40% = 2/5, so&lt;br&gt;
let 2x = son&#39;s age
let 5x = father&#39;s age&lt;br&gt;
The son&#39;s age in 10 years will be half his father&#39;s age then:&lt;br&gt;
{{{2x+10 = (1/2)(5x+10)}}}
{{{4x+20 = 5x+10}}}
{{{x = 10}}}&lt;br&gt;
The son&#39;s age is 2x=20; the father&#39;s age is 5x=50&lt;br&gt;
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