# How do you check that the solution to 2(5 - 2z) = 20 - 2(z - 1) is -5?

2(5−2z)=10-4z
20−2(z−1) = 20-2z+2
$- 2 z = 20 - 10 + 2$
$- 2 z = 12$
and thus $z = - 6$