To find the inverse all you do is swap your x and y then solve it through. for this one you gotta take f(x) and make it y
y = 1/4x - 12
then swap
x = 1/4y - 12
then solve it through
x - 12 = 1/4y
divide by (1/4)
and (x - 12)4 = y should be your answer
In order to solve a proportion you need to cross multiply, so you would do:
4x20 and 9xX and you would get...
9x=80
then divide by nine to get
x=8.8888888889
which is technically 8.9
12000 = 2x - 1500
12000 + 1500 = 2x
13500 = 2x
13500/2 = x
6750 = x <=== original price
