Question

Jose needs to memorize words on a vocabulary list for French class. He has memorized 20 of the words, which is four-fifths of the list. How many words are on
the list?

Answer 1

Answer:

25

Explanation:

In order to solve this the easiest way you can use equivalent fractions.

$\frac{4}{5} = \frac{20}{?}$

Since 4 times 5 equals 20 we can multiply 5 times 5 to get our answer.

$\frac{4}{5} * \frac{5}{5} = \frac{20}{25}$

25 is the answer. But, if we couldn't have gotten to 20 through the multiplication we could use a proportion. That would look like the initial problem but instead of a "?" we would use a variable. I will use t for total.

$\frac{4}{5} = \frac{20}{t}$

So now we have our problem set up. The next step is to cross multiply. 4 by t and 5 by 20.

$4t = 5 * 20\\4t = 100$

And now we can solve it like a normal algebra problem.

$\frac{4}{4}t = \frac{100}{4}\\t = 25$

Either way, we get 25.