1.


Multiply both sides by x:

Subtract from both sides Gx:

Then solve this equation:

2.


Multiply both sides by x:

Subtract from both sides Gx:

Then solve this equation:
Since x=months,
50x=y
Where x is the number of months times the monthly charge. Y is just the output, or end value.
I hope this helps!
~kaikers
X^2+2x^2-5x
((x^2)+2x^2)-5x
Pull the factors out
3x^2-5x=x(3x-5)
x(3x-5)
x(3x-5)*5x^2
5x(3x-5)*x^2
Final
5x^3*(3x-5)
0.3% of 12,000 = 36 Correct ans