Answer
$33.4lb/in^{2}$
Work Step by Step
By ideal gas law for fixed number of moles and volume :
$\frac{P}{T}=constant$
$T_{1}=61F=289.61K$, $P_{1}=30+14.7=44.7psi$
$T_{2}=100F=310.93K$
Now, $\frac{P_{1}}{T_{1}}=\frac{P_{2}}{T_{2}}$
or, $\frac{44.7}{289.61}=\frac{P_{2}}{310.93}$
or, $P_{2}=48.1psi$
Thus, gauge pressure =$48.1-14.7=33.4lb/in^{2}$
