Find the angles of a triangle if one of them is half the other and 80 less than the third.

Let the angles be x, y and z degrees. Let’s write down the condition of the problem in the form of formulas:
2 * x = y
x + 80 = z
Since the sum of the angles of a triangle is 180 degrees, then:
x + y + z = 180
Substitute the first two equations in the third and get:
x + 2 * x + x + 80 = 180
4 * x = 180 – 80
4 * x = 100
x = 25
Then
y = 2 * 25 = 50
z = 25 + 80 = 105
Answer: 25, 50, 105 degrees.