7 1/5:2 4/7-8 3/4:(10-(5 1/2) 2:4 2/5)+(3 1/8*2):(8 1/12-1 5/6) = 2 4/5 - 10 1/6 + 6 1/4 : 6 1/4 = 1 19/30 + 1 0/1 = 2 19/30
