I'd really appreciate your help, please no joke answers Find the distance from (7, -4) to y+3x - 5

Procedure would be apreciated

Image attached and an explaination I don't fully understsand

Achemist has 200 ml of a 10% sucrose solution. she adds x ml of a 40% sucrose solution. the percent concentration, y, of the final mixture is given by the rational function: the chemist needs the concentration of the final mixture to be 30%. how many milliliters of the 40% solution should she add to the 10% solution to get this concentration?

Terri makes a quilt using three sizes of fabric squares the side lenght of each fabric square is the square root of the area

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%