10+80+ 10

90-90

The result will be different from the direct calculation, because this question changes the operation order of filling in the blanks. After calculating 40-30= 10, add 50 and subtract 40. Now 40-30= 10 is finished, 50+30=80 is added, 50-40 is added, and finally it is reduced. Column type:

Original: 40-30+50-40

Now: (40-30)+(30+50)+50-40

90-90=0