Please help me with the question. I need help with the top question not the bottom

Closing a credit card usually _your debt ratio.a. increasesb. decreasesc. improvesd. has no effect on

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)

Your friend uses c=50p to find the total cost, c, for the people, p, entering a local amusement park what is the unit rate and what does it represent in the context of the situation?