tellsTo answer this question we can use the Combined Gas Law, which tell us that the pressure, volume, and temperature of one situation is equal to the second situation, now let's see how is this formula and how can we apply it to our question:
P1 * V1/T1 = P2 * V2/T2
Now in your question:
1 * 2/20 = 0.33 * 5.1/T2 (I did the transformation mmHg - atm, that makes the question easier, so 752 mmHg = roughly 1 atm and 253 mmHg = 0.33 atm)
2/20 = 1.683/T2
0.1 = 1.683/T2
T2 = 16.8°C