Question 627882
REplace A with proper expression where the fractions are equivalent: 
:
{{{7/((a+5))}}} = {{{((7a-35))/A}}}
factor out 7 in the 2nd numerator
{{{7/((a+5))}}} = {{{(7(a-5))/A}}}
divide both sides by 7, results:
{{{1/((a+5))}}} = {{{((a-5))/A}}}
Cross multiply
A = (a+5)(a-5)
A = a^2 - 25
Equiv:
{{{7/((a+5))}}} = {{{((7a-35))/((a^2-25))}}}