2х-5(х-4)=8        < -- раскроем скобки

2x - 5x +20 = 8

2x - 5x = 8 - 20

-3x = -12

x = -12 : (-3)

x = 4

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проверка:

2*4 - 5(4-4) = 8

    8 - 5*0 = 8

     8 - 0 = 8

Verified answer

2x- 5x+20-8=0

-3x+12=0

-3x=-12

x=4