Answer : The final pressure of the balloon will be, 1369.6 torr
Explanation :
Boyle's Law : It is defined as the pressure of the gas is inversely proportional to the volume of the gas at constant temperature and number of moles.

or,

where,
= initial pressure = 923 torr
= final pressure = ?
= initial volume = 2.30 L
= final volume = 1.55 L
Now put all the given values in the above equation, we get:


Thus, the final pressure of the balloon will be, 1369.6 torr