The sum of all angles in a triangle = 180 degree
So :
Angle x + Angle 5x + 72 = 180
x + 5x + 72 = 180
6x = 180 - 72
6x = 108
Divide both side by 6 :
6x/6 = 108/6
x = 18
x = 18
since all the angles are less than 90 degree so the triangle is an acute triangle,
as 5x = 90 thus one angle is of 90 degree
Thus triangle is Acute Right angle triangle
Answer : x = 18, acute right angle triangle