Any linear function is of the form y=mx+b
Here m is slope and b is y intercept.
Slope is difference in y divided by different in x values .
In the question for 5 persons cost is $100 and for 10 persons cost is $162.50
So the points are (5,100) and (10,162.50)
Slope m==12.50
We can find the value of b by taking m=12.50 and (x,y)=(5,100)
Substitute these values in y=mx+b
100=12.50(5)+b
100=62.50+b
Subtracting 62.50 both sides
b=100-62.50
b=37.5
a) Put m=12.50 and b=37.50 to get the equation
y=12.50x+37.50
b)Rate of change is the m value or the slope of the function.
Initial value that is (5,100) gives us one of the points to find the rate of change.