Вычислите 1) 2/5+3/5 2) 3/7-2/7 3) 7/20-3/20 4) 1/9+5/9 5) 6/23-3/23 6) 3/20+7/20 7) 13/29-2/29 8) 11/51+13/51 9)17/72-13/72
1) (2+3)/5=5/5=1; (3-2)/7=1/7; (7-3)/20=4/20=1/5; (1+5)/9=6/9=2/3; (6-3)/23=3/23; (3+7)/20=10/20=1/2; (13-2)/29=11/29; (11+13)/51=24/51=8/17; (17-13)/72=4/72=1/18