Answer
a) $T_L=10°C$: $COP_{HP}=29.3$
b) $T_L=-5°C$: $COP_{HP}=11.7$
c) $T_L=-30°C$: $COP_{HP}=5.86$
Work Step by Step
$COP_{HP}=\dfrac{1}{1-\frac{T_L}{T_H}}$
Given $T_H=35°C$
a) $T_L=10°C$: $COP_{HP}=29.3$
b) $T_L=-5°C$: $COP_{HP}=11.7$
c) $T_L=-30°C$: $COP_{HP}=5.86$