Question

How do I solve a percentage problem that already tells me the percentage:

36 is 40% of what number?

Answer 1

you do 36 divided by 0.4 to get 90

it’s the opposite of what you do to get the percent.

so you take the given and then turn the percent in decimal form and divide.

Answer 2

Answer: 90

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Step-by-step explanation:

In many problems like this, the word "is" often means "equals".

Also, the "of" means "multiply".

40% turns into the decimal form 0.40

This means the original sentence of "36 is 40% of what number" translates to the algebraic format 36 = 0.40x where x is the unknown number. Think of 0.40x as "0.40 times x".

To find x, we divide both sides by 0.40

x = 36/(0.40) = 90

Therefore, 36 is 40% of 90

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Check:

40% of 90 = (40/100)*90 = 0.40*90 = 36

40% of 90 = 36

The answer is confirmed.

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Another approach:

part/whole = percent/100

36/x = 40/100

36/x = 0.40

36 = 0.40x

0.40x = 36

x = 36/(0.40)

x = 90

About halfway through these steps, we effectively repeat what was mentioned in the first section.

Another slightly different pathway is to cross multiply, but you should get x = 90 as the final answer.