Answer:
7f
r = ----------- - 4
z
Step-by-step explanation:
I will assume that you meant:
7f
z = ------------
r + 4
Solve for r. Start by interchanging z and (r + 4):
7f
r + 4 = -----------
z
Now subtract 4 from both sides. This isolates r:
7f
r = ----------- - 4
z
