Let x, y, z and a are the first, second, third and fourth angles of the quadrilateral.

Given, the sum of three angles of a quadrilateral is 5 times the fourth angle

=> x + y + z = 5a

Now, sum of all the angles in a quadrilater = 360

=> x + y + z + a = 360

=> 5a + a = 360

=> 6a = 360

=> a = 360/6

=> a = 60

So, the fourth angle is 60 degree.