The answer is "Math".....but technically the official name for it is Mathematics.
The correct answer is 40.3 degrees
Its fairly simple, B*L*H. So 3 x 4 x 5 and you get 60 m^3
9 liters of fuel covered 81 km
1 liter of fuel would have covered 81/9 km = 9 km
22 liters of fuel would then cover = 22 * 9 = 198 km.
Slope is the change in Y over the change in X:
Slope = (1 - -5) / 4 -1)
Slope = 6/3 = 2