Question

30% of a number is 120. What is the number?

Answer 1

`400`

Explanation:

You divide `120/0.3=400`

You can double check by multiplying `400xx0.3=120`

Answer 2

`n=400`

Explanation:

If we choose `n` as the number, we can write an equation:

`30% " of " n = 120" "larr` now solve for `n`

`30/100 xx n =120`

`n = 120 xx 100/30`

`n = 400`

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Or we can write equivalent fractions for the numbers and percentages as a direct proportion:

if `120` is `30%`, then what number will be `100%?`

`120/30 = x/100" "(larr"numbers")/(larr"percents")`

`30x = 120xx100" "larr` cross multiply to get this

`x = (120xx100)/30`

`x =400`