Question

1. John and William leave their home traveling in opposite directions on a straight road. John drives20 miles per hour faster than William. After 4 hours they are 240 miles apart. Find both of theirrates.

Answer 1

we have the following:

John's rate = x mph

William's rate = x -20 mph

`\begin{gathered} v=(d)/(t) \\ d=d\cdot t \\ d=x+x-20=2x-20 \\ t=4 \end{gathered}`

d = d, therefore:

`\begin{gathered} 4\cdot(2x-20)=240 \\ 8x-80=240 \\ 8x=240+80 \\ x=(320)/(8) \\ x=40 \end{gathered}`

John's rate = 40 mph

Willams's rate = 40 - 20 = 20 mph