Here we can say that number of moles as well as pressure will remain same for the balloon
so here we can say by ideal gas equation
[tex]PV = nRT[/tex]
so here for constant pressure and constant number of moles we have
[tex]\frac{V_1}{T_1} = \frac{V_2}{T_2}[/tex]
[tex]\frac{1}{293} = \frac{V}{263}[/tex]
now by rearranging the equation we have
[tex]V = \frac{263}{293}[/tex]
[tex]V = 0.89 Liter[/tex]
so final volume will be 0.89 liter