Answer:
y = 50
Step-by-step explanation:
All triangle angles add up to 180 degrees.
To set this equation up, you need to add everything given in the triangle and set it equal to 180:
y + y + 80 = 180
Add like terms:
2y + 80 = 180
Subtract 80 from both sides:
2y + 80 = 180
- 80 - 80
___________
2y = 100
Divide both sides by 2:
y = 50
If you're unsure, you can plug in the 50 for y:
y + y + 80 = 180
50 + 50 + 80 = 180
100 + 80 = 180
180 = 180
