Answer
Please see the work below.
Work Step by Step
We know that
$\Delta r=r\alpha \Delta T$
We plug in the known values to obtain:
$0.1\times 10^{-6}m=0.5cm\times \Delta T(3.2)\times 10^{-6}-12\times 10^{-6}$
$\Delta T=\frac{-10^{-6}}{0.5\times 10^{-2}\times 8.8\times 10^{-6}}=-23K$
Now $\Delta T=T_f-T_i=-23K$
$\implies T_f=T_i-23K$
$T_f=330K-23K=307K$
