There is an entry fee for a shop of $5. The cost of chocolate per kilogram for the first 3 kg is $12/kg. After 3 kg, the cost becomes $10/kg.

What would be the total price if a child buys x kg of chocolates?

Also, draw the graph of the function.

Sketch the graph of the following piecewise function.

$u\left(x\right)=y=\{\begin{array}{c}\frac{2x^2-4x}{x-2},\text{ if }x\ne 2\\ 5,\text{ if }x=2\end{array}$

Let $C(x)$ be the total cost in dollars of electricity used by a factory from time $t=0$ to $t=x$ hours, where the cost rate is given by $c\left(t\right)=\begin{cases}0.5t+3;t\le4\\ 5;t>4\end{cases}$.

Find the formula for $C(x)$.