Question 1153474
.
<pre>

Let x = Sandy's age (the unknown under the question).

Then her son's age is (x-25) years.


From the condition,


    x = 3*(x-25) - 7.


Hence,

    x = 3x - 75 - 7

    x = 3x - 82

    82 = 3x - x

    82 = 2x

     x = {{{82/2}}} = 41.


<U>ANSWER</U>.  Sandy is 41 years old.
</pre>