Give the step-by-step reasoning process and then the final answer. Sasha heard that planting trees helps to reduce the local temperature. For each tree planted, the temperature drops .1 degree. A tree costs $6 to plant. If she got the local temperature to drop from 80 to 78.2, how much did it cost to plant the trees?
The temperature dropped 1.8 degrees because 80 - 78.2 = 1.8. She planted 18 trees because 1.8 / .1 = 18. It cost $108 to plant the trees because 18 x 6 = 108.
The final answer: 108.