1. (6/11+ 5/11) x 3/7=(11/11)x3/7=3/7
(6/11+ 5/11) x 3/7= 6/11 x 3/7 + 5/11x3/7=18/77 + 15/77=3/7
2. 3/5 x 7/9 - 3/5 x 2/9=3/5 x ( 7/9 - 2/9 )=3/5 x 5/9 =3/9
3/5 x 7/9 - 3/5 x 2/9= 7/15 - 2/15= 3/9
3. ( 6/7 -4/17 ) :2/5= 2/17:2/5=5/17
( 6/7 -4/17 ) :2/5=6/7: 2/5- 4/7 : 2/5=15/7- 10/7=5/7
4. 8/15: 2/11 + 7/15 : 2/11=44/15+ 77/30=11/2
8/15: 2/11 + 7/15 : 2/11= (8/15+ 7/15):2/11=15/15:2/11=11/2