-0.85×17分之8-18×7分之2+(18÷9分之7-17分之9×0.85)
=-17/20x8/17-18x2/7+18x9/7-9/17x17/20
=-17/20x(8/17+9/17)+18x(9/7-2/7)
=-17/20x1+18x1
=18-0.85
=17.15
-0.85×17分之8-18×7分之2+(18÷9分之7-17分之9×0.85)
=-17/20x8/17-18x2/7+18x9/7-9/17x17/20
=-17/20x(8/17+9/17)+18x(9/7-2/7)
=-17/20x1+18x1
=18-0.85
=17.15