11. If Jane loses four and a half pounds per week, how long will it take her to lose 21 and a half pounds?

4 and 12 lb per week is a rate. The base is the number of weeks, and the amount is the number of pounds. If we are looking for the number of weeks, we use the formula B = A/R

How many times does 4 and 1/2 go into 21 and 1/2? Since we are dividing mixed numbers, we will want to change them to improper fractions.

Invert and multiply

Since the answer comes out as an improper fraction, you might want to convert it to a mixed number. Divide the bottom into the top.

It would take her 4 and 7/9 weeks to lose that much.