№2.
- 17х + 2а + 3а + 3х + 4х = - 10х + 5а
- 10 * (- 1,25) + 5 * 0,02 = 12,5 + 0,1 = 12,6
№3.
7х - 15 = 5х + 13
7х - 5х = 13 + 15
2х = 28
х = 28 : 2
х = 14
---------------------------------
7 * 14 - 15 = 5 * 14 + 13
98 - 15 = 70 + 13
83 = 83
№4.
- 6 * (3 - х) = 2х +3 * (х - 4)
- 18 + 6х = 2х + 3х - 12
6х - 2х - 3х = - 12 + 18
х = 6
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- 6 * (3 - 6) = 2 * 6 + 3 * (6 - 4)
- 18 + 36 = 12 + 18 - 12
18 = 18