If you're describing a time, then it has to have a unit of time. We have no idea how much gas you're talking about, so second, minute, and hour are all possibilities.
The increase of the radius is a linear increase since we have the constant rate of 0.07 inches per second
The equation for a linear growth/decay is given by the form

where

is the rate of increase and

is the value of

when

We have

when
So the equation is 
The length of the radius when

seconds is


inches
he should know how much gallons he need to fill his car up
multiply 1.50 by the amount of gallons he need so he should know how much money to spend on that many gallons
hoped i helped and brainlist plz
The answer is 6 because you do this
1/3 of 18 divide 18 by 3 amd get 6