How many degrees are in the corner of a rectangle

You got a job selling magazines door-to-door. you are paid $100 per day plus $1.50 for each magazine you sell. which recursive formula models this situation?

Can someone me out here number 4 plz

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)