Answer
It will take him 450 minutes to read 90 pages.
Explanation
Luis can read 3 pages every 15 minutes.
You are trying to find how long it will take him to read 90 pages.
Set up this ratio.
[tex]\frac{15}{3} =\frac{x}{90}[/tex]
To get from 3 to 90, you multiply by 30. Do the same thing to 15.
15 times 30 is 450.
It will take Luis 450 minutes to read 90 pages.
