First, apply the distributive property:
-30 = 5(x + 1)
-30 = 5x + 5
Substract 5 from both sides:
-30 - 5 = 5x + 5 - 5
-35 = 5x
Divide both sides by 5:
[tex]\mathsf{\dfrac{-35}{5} = \dfrac{5x}{5}}[/tex]
[tex]\large{\boxed{\mathsf{-7 = x}}}[/tex]
Let's check the answer:
-30 = 5(x + 1)
-30 = 5(-7 + 1)
-30 = 5(-6)
-30 = -30
The answer is correct.