Ответ:

7х+139=15*13

7х=56

Х=8

294:(х+8) =21

Х+8=14

Х=6

(413 - х) : 12 + 27 = 60

(413 - х) : 12 = 33

413 - х = 33 * 12

413 - х = 396

х = 413 - 396

х = 17

41 - (216-3x)/34 = 35

41 - (216 - 3x) : 34 = 35

(216 - 3х) : 34 = 41-35

216 - 3х = 6 * 34

216 - 3х = 204

3х=216-204

3х=12

х=12:3

х=4