Anna talks us through the gas laws. 

There's no way round it, you just need to learn these. The definitions can glaze together, so pay attention to what the constant is in each gas law and go from there. Once you've got them down, the universal gas law makes sense. The main way to get muddled here is by mixing up your units- in a written question asking you to calculate an unknown value, make sure you convert all your known values to litres, kelvin and kPa before proceeding with any calculations!