Headphones cost $6 for 4 pairs. What is the price of 1 pair ?

Can someone pls ! pls answer all. no explanation needed..

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 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)

The measurement of one angle of a right triangle is 42° what is the measurement of the third angle? (there is no picture)