The temperature of the air mass would be 5°C after it rises.
Air temperature drops 1°C for every 100 m it rises:
1/100 = x/500
Cross multiply:
500*1 = 100*x
500=100x
Divide both sides by 100:
500/100 = 100x/100
5 = x
The temperature will drop 5°; 10-5 = 5°C for the new temperature.
