Calculating Speed and time

This morning we did a mathsbuddy activity and it was called Calculating Speed and what you have do is there will be a question here is a example. Distance traveled 210km time traveled 7hrs so now you have to take one 0 of the 21 so make it 21 then divide 40 by 7 then it will equal 3 then add the 0 back onto the 3 and it will be 30.