Answer:
New volume of the balloon will be 28.4 L.
Step-by-step explanation:
As the amount of gas and pressure of the gas remains constant therefore in accordance with Charles's law:

where
and
are volume of gas at
and
temperature (in kelvin scale) respectively.
Here
,
and

So
= 28.4 L
So new volume of the balloon will be 28.4 L.