A 3.0 L balloon at 300 K is placed in a cooler at 225 K. What is the volume of the balloon after it has been in the cooler?

P V = n R T

P same
n same
R same
so
V = k T
V1/T1 = V2/T2

V2 = (T2/T1) V1
V2 = (225/300) (3)