If a graph fails the vertical line test, it is not a function?

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

The scatter plot graph shows the average annual income for a certain profession based on the number of years of experience which of the following is most likely to be the equation of the trend line for this set of data? a. i=5350e +37100 b. i=5350e-37100 c. i=5350e d. e=5350e+37100

Tamera puts 15/4 gallons of gasoline in her car. which mixed number represents the gallons of gasoline? a) 2 3/4 gallons b) 3 1/4 gallons c) 3 3/4 gallons d) 4 1/2 gallons answer it's worth a lot of points!