Answer:
8y - 11
Explanation:
This is because if you add up all of the y-variables, it equals a total of 8. That is the length of the black line. Because the blue line and the green line represent this length, we can subtract the 11 of the known line to create an equation that would leave us with the green line, or to represent the length of the green line. Hope this helps if you didn't understand before.