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

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Answer 1 · 2017-07-02T16:43:51

$400$ $400$

You divide $\frac{120}{0.3} = 400$ $120/0.3=400$

You can double check by multiplying $400 \times 0.3 = 120$ $400xx0.3=120$

Answer 2 · 2017-07-02T20:54:32

$n = 400$ $n=400$

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

$30 % of n = 120 \leftarrow$ $30% " of " n = 120" "larr$ now solve for $n$ $n$

$\frac{30}{100} \times n = 120$ $30/100 xx n =120$

$n = 120 \times \frac{100}{30}$ $n = 120 xx 100/30$

$n = 400$ $n = 400$

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

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

$\frac{120}{30} = \frac{x}{100} \frac{\leftarrow numbers}{\leftarrow percents}$ $120/30 = x/100" "(larr"numbers")/(larr"percents")$

$30 x = 120 \times 100 \leftarrow$ $30x = 120xx100" "larr$ cross multiply to get this

$x = \frac{120 \times 100}{30}$ $x = (120xx100)/30$

$x = 400$ $x =400$