This set of points is on the graph of a function.

The inverse will have reverse coordinates.....so the points on the inverse  are

(-8, -2),  (9, 0)

f(x)  = 4x + 3

For f(x), write y

y = 4x + 3     subtract 3 from both sides

y - 3  =  4x    divide both sides by   4

[ y - 3 ] / 4  =  x     swap x and y

[x - 3] / 4  = y     for y, write f^-1(x)

f^-1 (x)  =  (1/4)x - 3/4

f(x)  = (1/4)x  + 10

y = (1/4)x + 10

y - 10  =  (1/4)x     multiply both sides by 4

4y - 40  =  x

4x - 40  = y

f^-1(x)  = 4x - 40