Answer:
x = 27
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Sum the given angles and equate to 180
90 + x + 23 + x + 13 = 180, that is
126 + 2x = 180 ( subtract 126 from both sides )
2x = 54 ( divide both sides by 2 )
x = 27
