465. Қосуды тиімді тәсілмен орындаңдар:13 1971) 8 +1122+917+1211) 2) 2120+53020 3035 2113 4+9 +2435 21​

:1/5-1/6 =6/30-5/30=1/30

3/4-1/3 =9/12-4/12=5/12

7/9-2/11 =77/99-18/99=59/99

3/4-4/9 =27/36-16/36=11/36

7/8-5/12 =42/48-20/48=22/48=11/24

11/12-11/18​=33/36-22/36=11/36