Gay-Lussac's law states the relationship between pressure of gas with temperature. It states that pressure of gas is directly proportional to temperature of gas at constant volume.
P/T = k
where P - pressure, T-temperature and k-constant
P1/T1 = P2/T2
where parameters for the 1st instance are on the left side and parameters for the 2nd instance are on the right side.
2500 atm/ 290 K = P/320 K
P = 2759 atm