How much should the pressure be increased in order to decrease the volume of a gas 5% at a constant temprature ?

By what percentage should the pressure of a given mass of a gas be increased so as to decrease its volume by 20% at a constant temperature?

By what percentage should the pressure of a given mass of a gas be increased so as to decrease its volume by 10% at a constant temperature?

In order to increase the volume of a gas by 10% , the pressure of the gas should be