Question

Which proportion could be used to solve the problem below:
378 is 84% of what number?

A. 84 over 100 = 378 over x
B. 84 over 100 = x over 378
C. 378 over 100 = x over 378
D. 100 over 84 = 378 over x

Answer 1

you should learn to translate the words into "math"

378 is 84% of what number?

378
is turns into =
84% turns into 84/100 or 0.84
of what number turns into " times x"
put that all together:

378 = 84/100 * x

Answer 2

that equation does not match any of your choices. so we have to fiddle with it
divide both sides by x to get
\[ \frac{378}{x}= \frac{84}{100} \]

Answer 3

it still does not quite match, but you can swap sides in an equation:
\[ \frac{84}{100}= \frac{378}{x} \]