# Ben was walking in Manhattan at a constant speed. He went along 5th avenue from 4th to 98th street. At 3:00 he was on 15th street, and at 4:30 he was on 45th street. When did he start and when did he finish his walk?

## Write an equation which could tell on what street N he was T minutes after he started to walk.

Ben was walking at a constant speed, and we know it took him $1 \frac{1}{2}$ hours to go the 30 blocks between 15th and 45th streets. $1 \frac{1}{2}$ hours = 90 minutes and $90 \div 30 = 3$, so he was walking at a pace of 3 minutes per block. He started at 4th Street, which is 11 blocks before 15th Street. $11 \cdot 3 = 33$, so we subtract 33 minutes from 3:00 to determine the start time of 2:27. The distance between 45th Street and 98th Street is 53 blocks. $53 \cdot 3 = 159$. 159 minutes is 2 hours and 39 minutes. If we add that to the time of 4:30 (which is when he reached 45th Street), we get 7:09 as his finish time.