The angles of a quadrilateral are 2a, 4a, 7a and 5a. The measure of angles of quadrilateral are:
40o, 80o, 140o and 100o
The sum of angles of a quadrilateral is 360o.
2a + 4a + 7a + 5a = 360o
18a=360o
a = 20o
So, the angles of a triangle are 40o, 80o, 140o and 100o.