Apply Boyle's law:
PV = const.
P = pressure, V = volume, the product of P and V must stay constant
Our initial P and V values are:
P = 0.52atm, V = 5.7L
Our final P and V values are:
P = ?, V = 2.0L
Set the products of each set of PV values equal to each other and solve for the final P:
P(2.0) = 0.52(5.7)
P = 1.48atm