Solve the system below algebraically:
4x-y=20
-2x-2y=10

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

Who long does it take to drive 150 miles at 45 miles per hour

What are the triple angle formulas? is it related to double angle identities?