Ответ:

Пошаговое объяснение:

(1/4)x + 4 = 20 - (1/12)x

3x + 48 = 240 - x

3x + x = 240 - 48

4x = 192

x = 192 : 4

x = 48

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(1/28)z + 7 = 13 + (1/7)z

z + 196 = 364 + 4z

4z - z = 196 - 364

3z = -168

z = -168 : 3

z = -56

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(1/12)y + 4 = 16 + (1/3)y

y + 48 = 192 + 4y

4y - y = 48 - 192

3y = -144

y = -144 : 3

y = -48