<span>1,6*(9а-3в)-(4в-6а) = </span>1.6*9a - 1.6*3b - 4b - 6a = 14.4a - 6a - 4.8b - 4b = 8.4a - 0.8b
2х-х=20
Х=20
Проверка: 2*20-20=20
40-20=20
1)729-5126-629+5126=100
2) 2435-7261+4261-1335=-1900
3) x-9=-14
х=-14+9
х=-5
4) -20-x=-13
-х=-13+20
-х=7
х=-7
5) x+19=10
х=10-19
х=-9