(7\15+7\30+4\5):(2-1\3-1\2)
7/15+7/30+4/5=7*2/30+7/30+4*6/30=(14+7+24)/30=45/30
2-1/3-1/2=2*6/6-2/6-3/6=(12-2-3)/6=7/6
45/30:7/6=45*6/30*7=9/7=1 2/7
17:(3\5+1\4)+(7\8-1\4)*(4\5)
3/5+1/4=3*4/20+5/20=17/20
7/8-1/4=7/8-2/8=5/8
17:17/20=20
5/8*4/5=1/2
20+1/2=40/2+1/2=41/2=20 1/2