Since AOC is a straight line, it measures at an 180 degree angle. This means that the angles on the line have to add up to 180.
Therefore, we could do 5y + 30 = 180 (Adding all the angles: y + 4y)
We would then solve it as a two-step equation
5y + 30 = 180
1. + 30 - 30 = 0
2. 180 - 30 = 150
3.
5y divided by 5 = y
150 divided by 5 = 30
y = 30
All in all, the value of y is 30. We can also check our work by substituting in the value of y
30 + 30 + 4(30) = 180
30 + 30 + 120 = 180
This equation is true so therefore, the value of y is 30.