It looks like you want to find what percentage should be added to 40 to make it 0. Let's analyze the question:
- You start with 40.
- You want to add some percentage of 40 to it.
- After adding, the result should be 0.
Mathematically: Let the percentage to add be x%x%x%. Then:
40+(x100×40)=040+\left(\frac{x}{100}\times 40\right)=040+(100x×40)=0
Simplify:
40×(1+x100)=040\times \left(1+\frac{x}{100}\right)=040×(1+100x)=0
Divide both sides by 40:
1+x100=01+\frac{x}{100}=01+100x=0
x100=−1\frac{x}{100}=-1100x=−1
x=−100%x=-100%x=−100%
Answer:
You need to add -100% of 40, which means subtracting 100% of 40 (i.e., subtract 40), to make it 0. In other words, to get from 40 to 0 by adding a percentage of 40, you must add -100% (subtract 40).
