Answer
$8\%$
Work Step by Step
By the definition of conditional probability: $P(B|A)=\frac{P(A\cap B)}{P(A)}$.
Hence here: $P(\text{more than 100\$ and faulty})=P(\text{faulty})\cdot P(\text{more than 100\$|faulty})=20\%\cdot40\%=0.2\cdot0.4=0.08=8\%$
