Ответ:
Пошаговое объяснение:
2)
5*3 + 7x - 12 = 3(x+13)
15 + 7x - 12 = 3x + 39
3 + 7x = 3x + 39
7x - 3x = 39 - 3
4x = 36
x = 36 : 4
x = 9
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3)
2 - 7y + 2(4y + 7) = 3*(-y)
2 - 7y + 8y + 14 = -3y
y + 16 = -3y
y + 3y = -16
4y = -16
y = -16 : 4
y = -4
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4)
7y - 1 - 3(y + 1) = 4(2y + 5)
7y - 1 - 3y - 3 = 8y + 20
4y - 4 = 8y + 20
8y - 4y = -4-20
4y = -24
y = -24 : 4
y = -6