Solve the each part in detail of given problem:

Problem: A high-pressure gas cylinder contains 60.0 L of toxic gas at a pressure of 1.00 x 10⁷ N/m² and a temperature of 21.0°C. Its valve leaks after the cylinder is dropped. The cylinder is cooled to dry ice temperatures (-78.5°C), to reduce the leak rate and pressure so that it can be safely repaired.

Part I: What is the final pressure in the tank, assuming a negligible amount of gas leaks while being cooled and that there is no phase change?

N/m²

Part II: What is the final pressure if one-tenth of the gas escapes?

N/m²

Part III: To what temperature must the tank be cooled to reduce the pressure to 1.00 atm (assuming the gas does not change phase and that there is no leakage during cooling)?

I need tutor help in the above problem.