Answer:
497 K
Step-by-step explanation:
Assuming that the volume of the balloon (and so, the gas) remains constant, we can solve the problem by using the pressure's Law:
"When a constant mass of an ideal gas is kept at constant volume, the pressure of the gas is directly proportional to its absolute temperature"
Mathematically:

where
p is the pressure of the gas
T is the absolute temperature
The equation can also be rewritten as

where:
is the initial pressure of the gas
is the initial temperature of the gas
is the final pressure of the gas
Solving for T2, we find the final temperature:
