Answer
$T=57C^{\circ}$
Work Step by Step
As the process is thermally isolated, hence
$Q_1+Q_2=0$
$\implies m_1c_1(T-T_{i1})+ m_2c_2(T-T_{i2})=0$
This can be rearranged as:
$T=\frac{m_1c_1 T_{i1}+m_2c_2T_2}{m_1c_1+m_2c_2}$
We plug in the known values to obtain:
$T=\frac{0.2(900)(373)+0.05(4187)(293)}{0.2(900)+0.05(4187)}=330K=330-273=57C^{\circ}$
