Answer:
y = x + 64
Explanation:
The total # of books she has read in the first row is 67, the difference between 67 and 3 is 64.
As you look at the other rows, you see as you subtract 64, you get the same number of additional books read.
Example: 67-64=3
77-64=13
87-64=23
97-64=33
x represents the number of additional books so if you add 64 to x you get the total number which is why the answer is the 3rd option