Question 178574
a)
(1) {{{c = mx + b}}}
(2) {{{c = 3x + 2500}}}
The average cost per animal would be {{{c/x}}}
It is possible to get rid of the {{{x}}} in this expression:
(2) {{{c = 3.00x + 2500}}}
{{{3x = c - 2500}}}
{{{x = (c - 2500)/3}}}
Then, going back to 
{{{c/x = c/((c-2500)/3)}}}
{{{c/x = c*(3/(c-2500))}}}
{{{c/x = (3c) / (c - 2500)}}} answer
If there were {{{500}}} animals,
(2) {{{c = 3x + 2500}}}
{{{c = 3*500 + 2500}}}
{{{c = 4000}}}
{{{c/x = (3*4000) / (4000 - 2500)}}}
{{{c/x = 12000 / 1500}}}
{{{12000 / 1500 = 8}}} dollars per animal
This should equal {{{c/x}}}
{{{c/x = 4000 / 500}}}
{{{c/x = 8}}}
OK