Cuz it can help you later on in the fuchure
Let the measures of three angles be 2x, 9x, 4x
Sum of the angles of a triangle = 180
2x+9x+4x = 180
15x = 180
x = 180/15 = 12
First angle = 2x = 2*12 = 24°
Second angle = 9x = 9*12 = 108°
Third angle = 4x = 4*12 = 48°
I hope it is helpful:D
