Study the graph shown below. It is a graphic of a car trip taken by Amber and Ken. The starting position (0,0) is their home.

Graph of position versus time, with position on the y axis from 0 to 75 miles and time on the x axis from 0 to 8.5 hours. Segment 1 goes from 0,0 to 1,30. Segment 2 goes from 1,30 to 3,50. Segment 3 goes from 3,50 to 4,50. Segment 4 goes from 4,50 to 5,70. Segment 5 goes from 5,70 to 6,70. Segment 6 goes from 6,70 to 7,30. Segment 7 goes from 7,30 to 8,0.

How far had they traveled after four hours of travel?

a
30 miles

b
40 miles

c
50 miles

d
60 miles