350 : (20 x X - 15) = 70
420 + (4 x X + 360) = 940
350 + (600 - 5 x X) = 450 ​

Первое не знаю

420 + (4 X + 360) = 940

4 X + 360 = 940 - 420

4 X + 360 = 520

4 X = 520 - 360

4 X = 160

X = 40

350 + (600 - 5 X) = 450

600 - 5 X = 450 - 350

600 - 5 X = 100

5 X = 600 - 100

5 X = 500

X = 100

18/3=6

6-1=5

5*5=25

a) (327х-5295): 57=389

(327х-5295): 57-389=0

327x-27468=0

x=84

б)   (27x+11)*315=11970

8505x+3465-11970=0

8505x=8505

x=1