How do you find unknown fractions

You take the information you're given, and you put it together with
everything you know about handling and working with fractions. 
When you have all of this, you're ready to get on the trail toward the
unknown fraction, and to know it when you see it.

That part about how to handle and work with fractions . . . that's what
you're learning in school.

B. 16is the absolute value