Help please.I don't understand this

Find the number of positive three-digit even integers whose digits are among 9, 8, 7,5, 3, and 1.

What is the reflection image of (5,-3) across the line y = -x?

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%