Answer:
By the time she achieves her 26 mile goal Andrea will have run 176 miles.
Explanation:
Since Andrea runs 4 miles every day, but she wants to increase her distance in order to run a 26 mile marathon and she decides to add 2 miles each day to her distance until she achieves her goal, to determine, if she starts with 6 miles today, how many miles will she have run in total, by the time she achieves her 26 mile goal the following calculation should be performed:
6 + 8 + 10 + 12 + 14 + 16 + 18 + 20 + 22 + 24 + 26 = X
14 + 22 + 30 + 38 + 46 + 26 = X
36 + 68 + 72 = X
36 + 140 = X
176 = X
So, by the time she achieves her 26 mile goal Andrea will have run 176 miles.