Q$3$:$-$ Solve the following problem:

A new Electrical Company had started producing an electrical circuit bourd that ean maxtmize the pro with a working lime of eight hours a day, for $26$ days a month; over $10$ months a year. An Engineer pt linear relationship between price and demand which has form of $D=\frac{a}{h}-\frac{1}{b}$ Knowtng that the maxtin adjusted selling price with no units equals $$120$ per unit, and maximum totat reventie $ $$18,000$ per Capacity for this company is $400$ circuit board$/$year$.$ List of the costs for $400$ units pet ycar are:

Costs$-$:

Rent of the building $=480\frac{\text{\$}}{m}$onth

Circuit board cost $=200\frac{\text{\$}}{?}$ month

Electricity cost $=120\frac{\text{\$}}{?}$ month

Forman cost $=0\mathrm{.}525\frac{\text{\$}}{h}r$

Labor in production cost$=300\frac{S}{m}on$ th

Printer ink cost $=20\frac{\text{\$}}{m}$onth

Packaging cost $=100\frac{\text{\$}}{?}$ month

Calculate $-$ :

A$.$ Write general equation of the total Revenue, and total Costs?

B$.$ Calculate maximum profit can gain per year? Are you sure this is the maximum pro?

C$.$ Find range of the profitable range?