A quadrilaterals angles = 360°
three angles are given, with the fourth as x: 90, 80, 74, x
Add all the angles together and set it equal to 360
90 + 80 + 74 + x = 360
Simplify. Combine like terms
x + 244 = 360
Isolate the x, subtract 244 from both sides
x + 244 (-244) = 360 (-244)
x = 360 - 244
x = 116
116° is your answer
hope this helps
