Racer's average driving speed for a 4-hour trip was 45 miles per
hour. During the first three hours he
drove 40 miles per hour. What was his
average speed for the last hour of his
trip?
A 70 miles per hour
B. 60 miles per hour
C. 50 miles per hour
D. 65 miles per hour

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10

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)

Which of the following is a solution of z^6 = 64i? 2(cos105° + isin105°) 2(cos120° + isin120°) 2(cos135° + isin135°) 8(cos15° + isin15°)