m represents measure of first angle
3m represents measure of second angle
m + 55 represents measure of third angle
Sum of angles equals 180°
m + 3m + m + 55 = 180 combine like terms
5m + 55 = 180 subtract 35 from both sides
5m = 125
m = 25
The three angles are 25, 75, and 80.
Check
29 + 75 + 80 = 180
180 = 180