Standard deviation is the average distance between two points on the graph. If the standard deviation (sd) is high, then the variables relationship is more spread out and unlike one another. The smaller the sd, the closer and less varied the variables are.
I added 12+5(2) and got 22. Since 12 was how many shots she made on the first day and she makes 2 more shots than the previous day I did 5x2 which is 10 and add them up it makes 22:)