Our R is a constant. So it's zero point 81 litres times ATM over moles times Kelvin. And our molarity, well, we don't have our molarity, but we do have our asthma pressure. So this is what we want to find. And we want to find this guy and use that to find our grams per mole or molar mass. Because remember, molar mass is the amount of mass per 1 mol.