For every 1,000 feet you go up in elevation, the temperature decreases by about 3.3°F
Given:
Temperature at the bottom of the mountain is 74°F
The top of the mountain is 5500 feet above you
Change (reduction) in temperature is 3.3 X 5500 / 1000
= 18.15°F
Temperature at the top of the mountain is 74°F – 18.15°F
= 55.85°F