I know the answer but what’s the work

What is x and y intercepts for y=x+7

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)

An internet company charges $8.95 per month for the first 3 months that it hosts your web site. then the company charges $11.95 per month for web hosting. how much money, in dollars, will the company charge for 8 months of web hosting?