Some can find to me the surface area

(40 points) i need some . an answer definition is appreciated as well.

An equation representing lyle’s hedge-trimming business is a = 12n - 300 where a is the amount of profit or loss in dollars and n is the number of hedges trimmed. how would the graph of lyle’s business change if the equation a = 10n - 300 represented his business? the graph would be flatter. the graph would be steeper. the graph would start closer to the origin. the graph would start lower on the y-axis.

What is the average rate of change for this function for the interval from x=2 to x=4 ?