The y-intercept is the y-value that corresponds to x=0. Here, we have a table that has x-values that differ by 12 and 24. We want to find the y-value that corresponds to an x-value 24 less than the lowest one on the table:
24 -24 = 0
We notice that when x-values differ by 24, the y-values differ by 10 -(-8) = 18. So, the y-value we want is 18 less than the lowest one in the table:
y = -8 -18 = -26
The (x, y) coordinates of the y-intercept are (0, -26).