help question for chemistry

Question

If a piston with a variable volume starts with a volume of 125.0 mL and pressure of 1.25 atm then expands to a new volume of 206.5 while the temperature remains constant, what is the new pressure?

Answer 1

P1 = initial pressure = 1.25 atm

V1 = initial volume = 125.0 ml

P2 = final pressure = ?

V2 = final volume = 206.5 ml

P1V1 = P2V2

(1.25 atm)(125.0 ml) = (P2)(206.5 ml)

P2 = (1.25 atm)(125.0 ml) / 206.5 ml

P2 = 0.757 atm