To find a linear function P(x) that expresses profit as a function of time, we need to find the slope of the line that represents the relationship between profit and time. The slope is defined as the change in y (profit) over the change in x (time).
In this case, the change in time is 4 years and the change in profit is $83,900 - $39,800 = $44,100. Therefore, the slope of the line is $44,100 / 4 years = $11,025/year.
Now that we have the slope, we can use the point-slope formula to find the linear function P(x):
P(x) = $11,025/year * x + b
We need to find the value of b that makes this equation correct for the given starting point (x = 1 year, P = $39,800). Plugging these values into the equation, we get:
$39,800 = $11,025/year * 1 year + b
Solving for b, we get:
b = $39,800 - $11,025/year * 1 year = $28,775
So the linear function that expresses profit as a function of time is:
P(x) = $11,025/year * x + $28,775