Question 1025228
<pre>
{{{f(x)=(x-5)/(x+1)}}}; {{{f(a)=3/5}}}

Substitute {{{a}}} for {{{x}}} throughout

{{{f(a)=(a-5)/(a+1)}}}; {{{f(a)=3/5}}}

Now substitute {{{3/5}}} for {{{f(a)}}}

{{{3/5=(a-5)/(a+1)}}}

Cross-multiply:

{{{3(a+1)=5(a-5)}}}

{{{3a+3=5a-25}}}

{{{-2a=-28}}}

{{{a=14}}}

Edwin</pre>