-5r + (-3) = 51
Add 3 to both sides:
-5r = 54
Divide both sides by -5 to get r alone:
r = -10.8
To check this, plug in -10.8 into the equation: -5(-10.8) + (-3) = 51
54 + (-3) = 51
54 - 3 = 51
51 = 51
This statement is true, so the answer is correct.