Выполни сложение и сделай проверку49+20; 58+21; 39+42; 19+51; 60+27; 23+29; 45+19; 56+9;

49+20=69; 69-20=40
58+21=79; 79-21=58
39+42=81; 81-42=39
19+51=70; 70-51=19
60+27=87; 87-27=60
23+29=52; 52-29=23
45+19=64; 64-19=45
56+9=65; 65-9=56

49+20=69 => 69-49=20
58+21=79 => 79-21=58
39+42=81 => 81-42=39
19+51=70 => 70-51=19
60+27=87 => 87-27=60
23+29=52 => 52-23=29
45+19=64 => 64-45=19
56+9=65 => 65-56=9