Найди сумму и разность чисел: 13/30 и 22/45; 3/14 и 4/21; 17/45 и 5/18.

в третьем примере получается 9/42+8/42=17/42

спасибо

13/30 + 22/45 = 39/90 + 44/90 = 83/90; 13/30 - 22/45 = 39/90 - 44/90 = - 5/90 = -1/18. 3/14 + 4/21 = 9/42 + 8/42 = 17/42; 3/14 - 4/21 = 9/42 - 8/42 = 1/42. 17/45 + 5/18 = 34/90 + 25/90 = 59/90; 17/45 - 5/18 = 34/90 - 25/90 = 9/90 = 1/10.

13/30+22/45 =39/90+44/90=83/9013/30-22/45=39/90-44/90= - 5/90 = - 1/183/14+4/21 = 9/42+8/42 =15/423/14-4/21 = 9/42 - 8/42 = 1/4217/45+5/18 = 34/90/+25/90 = 59/9017/45-5/18 = 34/90 - 25/90 = 9/90 = 1/10