30 min: 60min-30min= 30 min and 30 min is half an hour. So since 30 min is half an hour you divide 4 by 2 and get 2 miles.
45 min: 60min-45min= 15 min. 15 is one quarter of an hour so, since you are going 4mph. So you do 4mph divided by another for because there are four quarters in one hour, which gives you one mile. Then you 1 mile 3 times because 15+15+15=45. So the answer is 3 miles.
To round a number to the nearest 1000, look at the hundreds digit. If the hundreds digit is 5 or more, round up. If the hundreds digit is 4 or less, round down
