If 39 is added to a number, it will be 4 times as large as it was originally. What's the number?

When you answer this can you explain

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%

Olive's solar powered scooter travels at a rate of 30 miles per hour. what equation can she use to calculate her distance with relation to the time she traveled? h=hours m=miles 1. h=m+30 2. m=30h 3. m=h+30 4. h=30m