Since they are averaging 55 miles per hour, after 6 hours they have traveled the distance x, which satisfy the proportions:
miles hour
55 1
x 6
Cross multiplying, we find:
1 * x = 55 * 6
x = 330
So, since they started 60 miles north of Cleveland after they travel 330 miles south, they will have passed Cleveland and traveled to the south of= Cleveland the number of miles given by:
330 - 60 = 270
Therefore, they have traveled, after 6 hours, 270 miles south of Cleveland.