How can gas pressure be changed?
Gas pressure is created by the collisions between the molecules of gas in a container and the collisions of those molecules with the walls of the container.
The number of molecular collisions can be affected in three ways.
First you could change the amount of molecules in the system. More molecules would mean more collisions. More collisions, more pressure. Decreasing the number of molecules would decrease the number of collisions and thereby decrease the pressure.
Second you could change the energy of the system by chaining the temperature. More energy would make the molecules move faster. Faster molecules would mean an increase in the number of collisions, More collisions mean a higher pressure.
Decreasing the energy would slow the molecules down and create less collisions. Less collisions means a decrease in pressure.
Finally, you could change the volume. A smaller space would mean more collisions, and increase pressure. A larger volume would decrease the number of collisions and decrease the pressure.
I hope this was helpful.