Answer
73.5 mL
Work Step by Step
$V_{1}=45.0\,mL$
$P_{1}=1.60\,atm= 1.60\,atm\times\frac{760\, mmHg}{1\,atm}$
$=1216\, mmHg$
$P_{2}=744\,mmHg$
$T$ and $n$ are constant.
Boyle's law states that if temperature and amount of gas are constant,
$P_{1}V_{1}=P_{2}V_{2}$
$\implies V_{2}=\frac{P_{1}V_{1}}{P_{2}}=\frac{1216\,mmHg\times45.0\,mL}{744\,mmHg}$
$=73.5\,mL$
