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