propagated disturbance is a variation
First, you find what 20% of 10 gallons of gas would be. This will show how many gallons the car actually uses.
10 gallons x 20% =
10 x 0.20 =
2 gallons used
Then you subtract that number from the total 10 gallons to get how many gallons of gas would be wasted.
10 gallons - 2 gallons =
8 gallons of gas wasted
Differences in land elevation result in rainfall runoff, and allow some of the original solar energy to be captured as hydro-electric power (Figure 1). Hydro power is currently the world's largest renewable source of electricity, accounting for 6% of worldwide energy supply or about 15% of the world's electricity.
hope this helps
mark brainliest :)