Mario's Plumbing charges a $50 fee, plus $65 per hour of labor. Luigi's Plumbing represents their charges with the following function: f(x) = 75x + 30.
What is the difference in the companies' flat fees (y-intercepts)?

A. $10
B. $20
C. $25
D. $35

Create a question with this scenario you could ask that could be answered only by graphing or using logarithm. david estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x.