Hobby Lobby offered a 15% discount off the regular price of a lamp. The amount of the discount is $12. What is the regular price of the lamp?

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)

I'm confused on this could anyone me and show me what i need to do to solve it.

This is about circle theorems. someone asap : (