we know that the sum of measures of angles of a triangle is equal 180 degrees
in this case we can writing 180 = m<Q +m<R + m<S so
180 = 1x + 3x +6x
180 = 10x
x = 18
in this way we can calcule that the measure of obtuse angle
m<S = (6x)° = 6*18 = 108 degrees
