G10.1 The average of $p, q, r$ and $s$ is 5 . The average of $p, q, r, s$ and $A$ is 8 . Find $A$.
G10.2 If the lines $3 x-2 y+1=0$ and $A x+B y+1=0$ are perpendicular, find $B$.
$\begin{array}{l}p+q+r+s=20 \\ p+q+r+s+A=40 \\ A=20 \\ \frac{3}{2} \times\left(-\frac{20}{B}\right)=-1 \Rightarrow B=30\end{array}$