if the sum of the three angle of quadrilateral is equal to 1.5 times the sum of the three angle of a traingle ,what is the measure of the fourth angle of the quadrilateral?

Answer 1

.... 1.5 times the sum of the three angle of a triangle
---> 1.5(180) or 270°

so sum of 3 angles + x = 360°
270+x=360
x = 90°