3 Найдите х, если: a) (65 + x) : 2 − 21 = 30; б) (x · 58 – 24) : 2 = 191; в) 8432 – 3870 : x = 8346.

a) (65 + x) : 2 − 21 = 30

(65 + x) : 2 = 30 + 21

(65 + x) : 2 = 51

65 + x = 51 * 2

65 + x = 102

x = 102 - 65

x = 37

б) (x ⋅ 58 – 24) : 2 = 191

x ⋅ 58 – 24 = 191 ⋅ 2

x ⋅ 58 – 24 = 382

x ⋅ 58 = 382 + 24

x ⋅ 58 = 406

x = 406 : 58

x = 7

в) 8432 – 3870 : x = 8346

3870 : x = 8432 - 8346

3870 : x = 86

x = 3870 : 86

x = 45

Ответ: a) x = 37; б) x = 7; в) x = 45.