This pie chart is split into fourths each part of the chart being a different color. Blue, yellow, green, and red. Therefore there is four possible outcomes each outcome having a 25% chance.
The expression is 4x + 19 because it goes up in 4 (27-23 etc) however it doesn't start on 4 it starts on 23 so you have to add 19 because 4+19=23
Answer = 4x + 19