((-(17/24+(-9/40))+(11/48+31/80)):3_4/5)*1_ 5/7=
1)17/24+(-9/40)=85/120+(-27/120)=58/120
2) -(+58/120)=-58/120=-29/60
3)11/48+31/80=55/240+93/240=148/240=37/60
4)-29/60+37/60=8/60=2/15
5)2/15 : 3 4/5=2/15: 19/5=2/15* 5/19=2/3*1/19=2/57
6) 2/57* 1 5/7= 2/57* 12/7=24/399