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