Pls help? I will give brainliest!

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%

What is the value of m in the equation 1/2 m - 3/4n=16 when n=8

Using elimination, what is -4x+2y=-12 4x+8y=-24