1)12 3/7:4 5/6=87/7:29/6=87/7*6/29=18/7=2 4/7
2)8 1/2:14=17/2:1/14=17/28
3)4 2/5-5/8=22/5-5/8=22/5-5/8=176/40-25/40=151/40=3 31/40
4)3 31/40+2 4/7=5+217/280+160/280=5 377/280=6 97/280
5)6 97/280-17/28=1777/280-17/28=1777/280-170/280=1607/280
6)1607/280:33/56=1607/280*56/33=1607/165=9 122/165