What is the interquartile range of this data set?

Key: 1|5 means 15

You and a friend race across a field to a fence and back. your friend has a 50-meter head start. the equations shown represent you and your friend's distances dd (in meters) from the fence tt seconds after the race begins. find the time at which you catch up to your friend. you: d=∣−5t+100∣d=∣−5t+100∣ your friend: d=∣−313t+50∣∣

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Graph the linear function using the slooe and y intercept