Answer: P = 5.4 atm
Explanation: For this problem we will use Boyle's Law which is P1V1 = P2V2. Derive for P2, so the formula will become P2 = P1V1 / V2.
P2 = P1V1/V2
= 0.60 atm ( 27 L) / 3.0 L
= 5.4 atm
Cancel out the units of Liter L and the remaining unit is in atm.