<=> 4x - 4 - 3x - 3 = -20
<=> 4x - 3x = -20 + 4 + 3
<=> x = -13
4.(x - 1) - 3.(x + 1) = -20
4x - 4 - 3x - 3 = -20
(4x - 3x) - ( 4 + 3) = -20
x - 7 = -20
x = -20 + 7
x = -13
\(4.\left(x-1\right)-3\left(x+1\right)=-20\)
\(4x-4-3x-3=-20\)
\(x-7=-20\)
\(x=-20+7\)
\(x=-13\)