Question 1153556
<pre>
{{{ 525/(n+6) = (525/n) - 10}}}
Multiply both sides by n+6 and n, and simplify:
{{{ n^2 + 6n - 315 = 0 }}}
{{{ n = 15 }}} and/or {{{ n = -21 }}}

Discard negative solution,  {{{ highlight( n = 15 )}}}

Check:

525/15 = 35  and  525/(15+6) = 525/21 = 25,  the difference is 10 so this checks out ok.