8 3/10+9 5/15-1 10/15

8 3*3/30 + 9 5*2/30 - 1 10*2/30 = 8 9/30 + 9 10/30 - 1 20/30 = 17 19/30 - 1 20/30 = 16 49/30 - 1 20/30 = 15 29/30

83/10+140/15-25/15=249/30+80/30-50/30=279/30=9 9/30