For this we want to use Boyle's Law. Boyle’s law states that the pressure and volume of a fixed quantity of a gas are inversely proportional under constant temperature conditions. The formula for this is P1V1 = P2V2. We want to solve this out so it equals V2 (Volume 2). So P1V1 / P2 = V2. Then plug in your values for the variables. So (101)(4.2) / 235 = V2; so 424.2 / 235 = V2. The final volume equals 1.81. I hope this helps, If not I am very sorry.