We have to find the formula for a two-dimensional vector field which has all vectors parallel to the x-axis and all vectors on a horizontal line having the same magnitude.
When all vector parallel to x- axis then
v(x,y)=0
Then, the vector field can be written as
When all vectors on a horizontal line having the same magnitude then
To find the number of miles driven on one gallon, divide 420 by 20. that would be 21. multiply 21 by 65 to find the number of miles you can drive with 65 gallons.