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? Let's think first. Chain of thought:
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.
Therefore, the answer is 40.