The equation 7(x-1)=-21 has to be solved for x
=> x - 1 = -3
=> x = -3 + 1
=> x = -2
The solution of the equation is x = -2
I have a tendency to love to use the distributive property, so I will show you how to find the answer by doing so.
7(x-1) = -21
7x-7 = -21
7x = -14
x = -2
As you can see, you arrive at the same answer, and I don't think it's necessarily any more work.