In this example, y is equal to 8.
In order to find this, first note that the two x value expressions create a straight line. That means when we add them together they will equal 180. this will give us a value for x.
x + 10 + 10x - 61 = 180
11x - 51 = 180
11x = 231
x = 21
Now that we have the value of x, we can do the same for the straight line created by the x + 10 angle and the 18y + 5 angle.
x + 10 + 18y + 5 = 180
(21) + 10 + 18y + 5 = 180
36 + 18y = 180
18y = 144
y = 8