Consider the question. Jamie is a firefighter. One day an emergency call comes in from Mrs. Thompson, an elderly woman whose cat can't get down a 20-foot tree. The last time Jamie rescued a cat, he got it down from a 6-foot tree and had to climb 12 rungs of his ladder. How many rungs does he have to climb this time to get the cat down from the tree?
 What is the step-by-step reasoning process to arrive at the answer: 40?

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Jamie needed 12 / 6 = 2 rungs per foot of the tree to save the first cat. To climb a 20 - foot tree, Jamie needs 20 * 2 = 40 rungs.