To find what the number is, we need to set up proportional fractions. Currently, we have 8% of a number is 20. To set up our fractions, put 100% under 8% as a fraction first.
It should look like this: 8/100 (hint: per-cent means per-hundred).
Now, we have 20 out of a number, x. This is because we are claiming that 20 is 8% of a number (if we just reword the question without changing the concept). It should look like this: 20/x.
Our proportional fractions are: 20/x = 8/100.
To solve for this, we need to cross-multiply the denominator of 8/100 (bottom number, 100) with the numerator of 20/x (top number, 20).
This product equation should look like this: 20 x 100 (when simplified, we get 2000).
Now, we need to cross multiply the numerator of 8/100 (top number, 8) with the denominator of 20/x (bottom number, x).
This product equation should look like this: 8x.
Now that we've cross-multiplied, set our two products as an equation.
8x = 2000.
To solve for x, divide both sides by 8 (remember, what you do to one side of an equation, you must do it to the other).
