Приведите дроби к общему знаменателю: 2/5 и 2/7; 3/5 и 3/4; 1/9 и 2/3; 3/7 и 1/2; 3/4 и 1/5; 11/39 и 7/13; 3/14 и 5/7; 5/64 и 5/32; 2/25 и 11/50; 1/23 и 17/46; 110/52, 9/28 и 2/7; 10/56,80/70 и 40/35; 18/144 и 19/12; 4/15, 23/78 и 35/30; 1цел. 19/120 и 4цел