Item. Andrew buys books and videos in a store. He uses the expression $6b + $12v to find the cost of what he is buying, where b is the number of books and v is the number of videos he buys. b Use the expression to find the total cost of 4 books and 5 videos. Show work or explain how you found it PLEASE HELP ME!​

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3

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)

Acircle has a circumference of 7.850 units. what is its radius?