Problem: Two boys are 1250 meters apart when one begins walking toward the other. If one walks at a rate of 2 meters per second and the other, who starts walking toward the first boy four minutes later, walks at the rate of 1.5 meters per second, how long will it take for them to meet?

Step 1: Boy 1 has a head start of 4 minutes. Converting all measurements to seconds: $\displaystyle 4(60)= 240$ seconds.

Step 2: Here is where I am having difficulties. The author states "Because the rate is given in meters per second, all times will be converted to seconds.) So he has traveled $\displaystyle 240(2)=480$ meters. Why did we take the head start converted into seconds of $\displaystyle 240 $ and multiply it by $\displaystyle 2$ to get $\displaystyle 480$ meters?

Googled around for it and I am confused because meters is a unit of distance, and seconds is a unit of time.