we know that the unit for velocity is m/s. then we put the values in it.
m/s= 1000m/20min
the SI unit for time is second then here we change the minutes into second, so we get 1200s. so
m/s= 1000m/1200s
m/s= 0.833m/s
it is the answer i hope it will help you and please send me thanks