First we need to convert everything into SI units.
The initial volume of the gas is (keeping in mind that [tex]1 L = 0.001 m^3[/tex]:
[tex]V_i = 5.0 L = 0.005 m^3[/tex]
The initial pressure of the gas is (keeping in mind that [tex]1 atm = 1.01 \cdot 10^5 Pa[/tex]:
[tex]p_i = 1.50 atm=1.52 \cdot 10^5 Pa[/tex]
The final pressure of the gas is (keeping in mind that [tex]760 mmHg = 1 atm=1.01 \cdot 10^5 Pa[/tex])
[tex]p_f = 1240 mmHg = 1.65 \cdot 10^5 Pa[/tex]
At constant temperature, the product between pressure and volume of the gas is constant, so we can write
[tex]p_i V_i = p_f V_f[/tex]
from which we find the final volume of the gas:
[tex]V_f = \frac{p_i V_i}{p_f} = \frac{(1.52 \cdot 10^5 Pa)(0.005 m^3)}{1.65 \cdot 10^5 Pa} =0.0046 m^3 = 4.6 L[/tex]
