1)5(x-4)=x+8 2)9-7(x+3)=5-6x 3)(7x+-7)=8 4)0,4(6-4t)=1,9-0,5(3t-7)

1)5х-20=х+8
  5х-х=8+20
  4х=28
  х=7
2)9-7х+21=5-6х
  -7х+6х=5-9-21
  -х=-35
  х=35
3)7х+9-11х+7=8
  7х-11х=8-9-7
  -4х=-8
  х=2
4)2,4-1.6t=1.9-1.5t+3.5
  -1.6t+1.5t=3.5+1.9-2.4
  -0.1t=3
  t=-30