Resposta :
a) 5x - 40 = 2 - x
5x + x = 2 + 40
6x = 42
x = 7
_____
b) 20 + 6x = - 2x + 26
6x + 2x = 26 -20
8x = 6
x = 6/8
x = 3/4
_____
c) 3,5x + 1 = 3 + 3,1x
3,5x - 3,1x = 3 - 1
0,4x = 2
x = 5
Espero ter ajudado
a) 5x - 40 = 2 - x
5x + x = 2 + 40
6x = 42
x = 7
_____
b) 20 + 6x = - 2x + 26
6x + 2x = 26 -20
8x = 6
x = 6/8
x = 3/4
_____
c) 3,5x + 1 = 3 + 3,1x
3,5x - 3,1x = 3 - 1
0,4x = 2
x = 5
Espero ter ajudado