Final answer:
The Ybarras need to drive an additional 125 miles before they stop for lunch in Roseburg (R), given that they have already traveled 55 miles and Roseburg is at the midpoint of their 360-mile trip.
Step-by-step explanation:
The student is asking how much farther they must travel before they stop for lunch at Roseburg (R), which is the midpoint of their 360-mile trip from Springfield (S) to Junction City (J). Since they have already covered 55 miles this morning, we need to calculate the remaining distance to the midpoint. The total distance to the midpoint is half of 360 miles, which equals 180 miles.
To find the remaining distance, we subtract the distance they have already traveled (55 miles) from the midpoint distance (180 miles).
180 miles (midpoint) - 55 miles (already traveled) = 125 miles.
Therefore, the Ybarras need to drive an additional 125 miles to reach Roseburg (R) for lunch.