Its 12y - 9 because when u add twelve pluus 12 it 24 then -21 is to 3 which 12 - 9 is 3
<span>5(-4) + 2y = -20
-20 + 2y = -20
2y = -20 + 20
2y = 0
y = 0</span>

Divide both sides by
to get


Substitute
, so that
. Then



The remaining ODE is separable. Separating the variables gives

Integrate both sides. On the left, split up the integrand into partial fractions.




Then

On the right, we have

Solving for
explicitly is unlikely to succeed, so we leave the solution in implicit form,

and finally solve in terms of
by replacing
:



Answer:
domain all real numbers
range all real numbers
the cost of his monthly cable is $40.50 when you plug in 4