The answer is 93
If we sorted out the number of each hours, the sequence will look like this
57 _ 69 _ 81 _ x _ 105
(in which x is the fourth hour of work)
We can see from the sequence that each hours, the mailman add additional 12 letters.
(69 - 57 = 12)
(81 - 69 = 12) . . . . proof
So, the amount of letters on the fourth hour would be:
81 letters + 12 letters = 93 Letters
Easiest way is to find out first how many she runs in a week. For that you can multiply the number of hours she runs a weekday by 5. (3.2*5) That should be 16. Now, since you want to know how many miles she will run in a span of 6 weeks you must multiply it by 6 now. That is 96. Since you know that, let's move on to the weekends. It is 1.5 per weekend day or 3 per weekend. Now you have to multiply 3 by 6 because you want to know for six weeks. Since you have both your numbers now, 18 and 96, you can add them to make a final of 114.
