You didn't provide more information regarding triangle but from given options, it seems that triangle has ratio from shortest side to longest side would be 5 : 12 : 13
So 13 would be hypotenuse since it is longest.
Now A cannot be right angle because tangent is not defined at 90°.
Also tan(A) would be ratio of opponent side to adjacent side (think SOH CAH TOA)
So either opposite side would be 5 or 12, and adjacent side would be 12 or 5 respectively.
So the answer is either 5 / 12 or 12 / 5 but only option provided is 12/5 so that would be your answer.
Final answer: 12 / 5
Y=1 we can check this by looking at the slope of the line: m=

so m=0. By looking at the graph we know our y-int is 1. By plugging in this information into the equation of a line we get the following: y=0x+1. That is y=1
2.25*x=10
Which x is the number of books purchased
Solve for x
X=10÷2.25
X=4.44