At what temperature was the gas in a closed vessel if, when it was heated at T = 300 K, the pressure increased 1.5 times?

These tasks: a closed vessel (therefore, we are considering an isochoric process); ΔT (change in gas temperature) = 300 K; P2 (final pressure) = 1.5P1 (initial pressure).
The initial gas temperature in a closed vessel is determined from the proportion: P1 / T1 = P2 / T2.
P1 / T1 = 1.5P1 / (T1 + ΔT).
T1 + ΔT = 1.5T1.
1.5T1 – T1 = ΔT = 0.5T1.
T1 = ΔT / 0.5 = 300 / 0.5 = 600 K or 327 ºС.
Answer: The gas was kept at a temperature of 327 ºС.