Resposta:

5(1-x)-2x+1=-3(2+x)

5 -5x -2x+1 = -6 -3x

5 + 1 -5x-2x = -3x -6

6 -7x = -3x -6

-7x +3x = -6 -6

-4x = -12

x=-12/-4

x = 3