Can anyone help me on this question?

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)

What are the greatest common factor of 75 and 30

Ellie spent $88.79 at the computer stote. she had $44.50 left to buy a cool hat. how much money did she originally have? write and solve an equation to answer the question.