# Barb wants to get 8 out of every 10 questions right on her test. If there are 35 questions on the test, how many Barb want to get right?

##### 1 Answer

She will want to get

#### Explanation:

Barb wants to get a certain **proportion** of the questions right. That proportion is "8 right for every 10 answered". This can be written as the **ratio** (or fraction) *one* of them, and the other will "tag along" to keep the proportion constant.)

Let

Since there are 35 questions on the test, we seek a ratio *equal to #"8 right"/"10 total"#* in the form of

#8/10=x/35#

Cross-multiply:

#8 xx 35 = 10 xx x#

#" "280=10x#

Divide both sides by 10:

#" "28 = x#

And there it is—the number of questions Barb needs to get right is

We can check this: