(-6 7/8 + 7 1/5) : 3/4 + ( 4 21/40 - 5 1/4) : 1 9/20= - 1/15
1) -6 7/8 + 7 1/5= -6 35/40 + 7 8/40= -6 35/40 + 6 48/40= 13/40
2) 4 21/40 - 5 1/4= 4 21/40 - 5 10/40= 4 21/40 - 4 50/40= - 29/40
3) 13/40 : 3/4= 13/40 * 4/3= 13/10 * 1/3= 13/30
4) - 29/40 : 1 9/20= - 29/40 : 29/20= - 29/40 * 20/29= - 1/2
5) 13/30 + (-1/2)= 13/30 - 15/30= - 2/30= - 1/15