bonjour
1) 1/9+17/27
(1x3)/(9x3)+17/27
3/27+17/27
20/27
2) 9/5-17/40
(9x8)/(8x5)-17/40
72/40-17/40
55/40
(5x11)/(5x8)
11/8
3) 4/9+11/81
(4x9)/(9x9)+11/81
36/81+11/81
47/81
4)8/7-2/77
(8x11)/(7x11)-2/77
88/77-2/77
86/77
5)6/48+8/6
6/48+(8x8)/(6x8)
6/48+64/48
70/48
(35x2)/(24x2)
35/24
6)9+7/3
27/3+7/3
34/3