Answer
See the answer below.
Work Step by Step
From the conservation of energy principle:
$10\ g\times 0.129\ J/g.K\times (T-100)+$
$10\ g\times 0.385\ J/g.K\times (T-0)+$
$150\ g\times 4.184\ J/g.K\times (T-20)=0$
$1.29(T-100)+3.85(T-0)+627.6(T-20)=0$
$632.74\ T=12681$
$T=20.04^{\circ}C$