let 'x' be the coefficient of the ratio
then you'll have it as x:2x:3x
remember that the sum of the interior angles of the triangle is 180.
adding all the interior angles and equating it to 180, you'll have the equation as:
x + 2x + 3x = 180
6x = 180
x = 30 ----first angle
2x = 2(30)
2x = 60 -----second angle
3x = 3(30)
3x = 90 ----third angle
therefore the three interior angles of the triangle are 30,60, and 90 degrees
