88 minutes (1 hour and 28 mins)
Since 5 miles takes 40 minutes, multiplying both numbers by 2 gets you to 10 miles in 80 minutes. To get the extra 1 more miles you have to find the unit rate
5 miles in 40 minutes : divided both numbers by 5 to get
1 mile in 8 minutes
add the one mile in 8 minutes to the 10 miles in 80 mins and you get 11 miles in 88 minutes
If they sold 89 calendars over 4 weeks, the 'equation' would look like (x = average calendars sold over 4 weeks):

If you solve it, you get:

Which is equal to
22.25. Hope this helps!
What you must do for this case is to follow the following steps.
1) Rewrite the expression completely.
2) make a double c.
3) Factor each quadratic expression correctly.
4) cancel similar terms.
Answer: 2n See attached images.
5/4 is the constant of proportionality
5.5-3b = 2b-6.25
5.5+6.25 = 2b+3b
11.75 = 5b
11.75/5 = 5b/5
2.35 = b