The exit for Freestone is built midway between Roseville and Edgewood, therefore the distance from O to the new exit is (1/2)*(33+55) = 44 mi.
Let x = distance from Midtown to the new exit. Because the distance from O to the new exit is equal to (x + 17), therefore x + 17 = 44 x = 44 - 17 = 27 mi.
Answer: When the new exit is built, the distance from the exit for Midtown to the exit for Freestone will be 27 miles.