Question 1144696
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            The given instructions in the post only make the solution harder.


            Let me to present you my solution in much more simple way.



<pre>
Let x be the John age.

Then the Joan age is (x+4) years, according the condition.


We are given  

    x + (x+4) = 126.

Hence,  

    2x + 4 = 126,

    2x     = 126 - 4 = 122,

     x               = 122/2 = 61.


37 years ago, when they were married,  John was  61 - 37 = 24 years old.

Joan was  24+4 = 28 years old at that time.    <U>ANSWER</U>
</pre>

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It is a bad teacher who instructs to solve a problem in a hard way, without any reason.