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

Jul 2, 2017

$400$

#### Explanation:

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

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

Jul 2, 2017

$n = 400$

#### Explanation:

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

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

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

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

$n = 400$

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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")

$30 x = 120 \times 100 \text{ } \leftarrow$ cross multiply to get this

$x = \frac{120 \times 100}{30}$

$x = 400$