Final answer:
To calculate other percentages based on the known value of 40%, you would determine the actual amount that 40% represents and then use that amount to find different percentages of the same total. Multiplying, adding, or dividing the 40% by another percentage does not provide an accurate method for finding different percentages.
Step-by-step explanation:
When it comes to using 40% to help calculate other percentages, the correct method is not to multiply, add, or divide by the desired percentage. Instead, you would use the 40% as a starting point to understand the part of the total you are working with. For instance, if you know something is 40% of a total, and you want to find out what 50% of that total would be, you can set up a proportion or use algebra to solve for the new percentage. To calculate other percentages based on a known percentage like 40%, you would generally find the actual number represented by the 40%, and then you could use that actual number to find other percentages of the same total. You might also use 40% to find the complement by subtracting it from 100%, which would give you 60% as the complementary percentage.