Remark
Three angles add to 180o.
The smallest angle = x
The middle angle = 2x
The largest angle = 3x
Solve
x + 2x + 3x = 180
6x = 180
x = 180 / 6
x = 30
Answers
The smallest angle is 30
The middle angle is 30*2 = 60
The largest angle is 30*3 = 90
This is a 30 - 60 - 90 right triangle