I1.1 If the average of $a, b$ and $c$ is 12 , and the average of $2 a+1,2 b+2,2 c+3$ and 2 is $P$, find the value of $P$.
$\begin{array}{l}a+b+c=36 \ldots \ldots(1) \\ P=\frac{2 a+1+2 b+2+2 c+3+2}{4}=\frac{2(a+b+c)+8}{4}=\frac{2 \times 36+8}{4}=20\end{array}$