(-6 7/8 + 7 1/5) : 3/4 + (4 21/40 - 5 1/4) : 1 9/20 помогите

(-6 7/8 + 7 1/5) /(3/4) + (4 21/40 - 5 1/4)/(1 9/20)= (-55/8+36/5)*(4/3)+(181/40-21/4)*(20/29)= (-275+288)/40*(4/3)+(181-210)/40*(20/29)=13/30-1/2=-1/15