The best thing to do is to divide the amount she has driven (357.9) by the miles (21) As you're looking for an estimate, you have to round them. 357.9 rounds to 360 21 rounds to 20 Therefore, you've got to divide them 360/20= 18 Therefore, Ellen has driven approximately 18 miles Hope this helps :)
When looking for an estimate, you have to round your numbers 21 rounded would become 20 and 357.9 would become 360. So next you would divide the numbers.
360 ÷ 20 = 18
So, Ellen would have used approximately 18 gallons of gas.
