Question 204538
first angle = x
second angle = y
third angle = z

x = 3y
z = y - 20

in a triangle, the sum of its angles are 180 degrees
x + y + z = 180
3y + y + y - 20 = 180
5y - 20 = 180
5y = 180 + 20
5y = 200
y = 200/5
y = 40
x = 3y = 3 * 40 = 120
z = y - 20 = 40 - 20 = 20

so,
the first angle is 120 degrees
the second angle is 40 degrees
the third angle is 20 degrees