80. 1) 43x + 72 = 502; 3) 19y 200 = 47;
81. 1) (x + 58) – 37 = 91;
3) 69 – (y – 28) = 13;
82. 1) 321 + (x + 13). = 450;
3) 204 - (x + 29) = 100;
83. 1) (x – 23) · 14 = 56;
3) 205 : (y - 27) = 41;
5) 89. (6 + 13) = 7120;​

43х+72=502

43х=502-72

43х=430

Х=10

19у-200=47

19у=47+200

19у=247

У=13

(Х+58)-37=91

Х+58-37=91

Х=91+37-58

Х=70

69-(у-28)=13

69-у+28=13

-у=13-28-69

-у=-84

У=84

321+(х+13)=450

321+х+13=450

Х=450-13-321

Х=116

204-(х+29)=100

204-х-29=100

-х=100+29-204

-х=-75

Х=75

(х-23)*14=56

14х-322=56

14х=56+322

14х=378

Х=27

205:(у-27)=41

У-27=205:41

У-27=5

У=5+27

У=32