max is going 20km an hour, how much will he travel in 5 minutes?

5 minutes  =  1/12 hr

So

20 km / hr  x   1 / 12 hr   =    [ cancel   hr  ]

20/ 12  km  =

5 /3  km

Set up direct proportion: $\frac{20*5}{60}=\frac{100}{60}=\frac{10}{6}=\boxed{\frac{5}{3}}$