A reasonable function is W = 7F + 5000
Where W is the weight of the plane and F is the number of gallons of fuel.
The domain is the set of possible values for F. That is from 0 (empty tank) to 400 (full tank).
So the domain is F = [0,400], or what is equivalente 0 ≤ F ≤ 400.
The range is the set of values of W.
The minimum value of W is when F = 0 => W = 7(0) + 5000 = 5,000.
The maximum value of W is when F = 400 => W = 7(400) + 5000 = 7,800
So the range is W = [5,000 ; 7,800], pr 5000 ≤ W ≤ 7,800.
