Answer
$T=106.22^{\circ}C$
Work Step by Step
First we calculated the pression exerted by the piston:
$A=150cm^2*\frac{1m^2}{10000cm^2}=0.015m^2$
$W=mg=40kg*9.81\frac{m}{s^2}=392.4N$
$P=\frac{W}{A}=\frac{392.4N}{0.015m^2}=26.16kPa$
$P_{abs}=100kPa+26.16kPa=126.16kPa$
Interpolating from table A-5:
$T=106.22^{\circ}C$
