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

2 Answers
Jul 2, 2017

400

Explanation:

You divide 120/0.3=400

You can double check by multiplying 400xx0.3=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

30/100 xx n =120

n = 120 xx 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")

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

x = (120xx100)/30

x =400