Charles' Law states that as temperature decreases, the volume of a gas decreases with it. As temperature increases, the volume of a gas increases as well. Thus, we say that the temperature and the volume of a gas are directly proportional. The equation that we use to solve this problem reads as follows:
V1/T1 = V2/T2
Remember that T1 will always be the temperature that you are trying to calculate, so:
6.24L(T1) = 5.17L(45.0 C)
6.24(T1) = 232.65
Therefore, T1 = 37.22 C