1)5*х+х-3*х+12=33-18 2)9*х-2*х-5*х=64-6*7 3)7*х-5*х+4*х-38=15*2+4

1) 5*x+x-3*x+12 = 33-18
12 + 3*x = 33-18
12 + 3*x = 15
x = 3 / (3) 
x = 1

2)9*x-2*x-5*x = 64-6*7
  2*x = 64-6*7
  2*x = 22
  x = 22 / (2)
  x = 11

3)7*x-5*x+4*x-38 = 15*2+4
 -38 + 6*x = 15*2+4
 -38 + 6*x = 34
  x = 72 / (6)
  x = 12