Answer:
T₂ = 392 K
Explanation:
Given that,
Initial volume of the hot air balloon, V₁ = 55500 m³
Initial temperature, T₁ = 21°C = 294 K
Final volume, V₂ = 74000 m³
We need to find the final temperature inside the balloon. The relation between the temperature and volume is given by charles law i.e.

Where
T₂ is the final temperature
So,

So, the new temperature is 392 K.
I think the best word here would be compress. It is to compress that is defined as to squeeze a gas into a smaller space. Compression is the reduction of volume which cause an increase in pressure of the gas. Hope this answers the question. Have a nice day.
Derived from a greek word meaning “Earth” in most cases it means “global” or relate to the Earth somehow