Jenny bought 7 t-shirts, one for each of her seven brothers, for $9.95 each. The cashier charged her an additional $13.07 in sales tax. She left the store with a measly $7.28. How much money did Jenny start with?

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)