X = 30 the line at the bottom is equal to 180 degrees and your middle is 90. There are three points so your expression is 3x = 90 , fill in the x with 30 so its equal. ( because 3 x 30 = 90 )
X= 30 I hope you understand the work It can be assumed that the line is 180 degrees so you must subtract the given 90 degree angle in the middle The equation can then be 3x=90 because if there is a x value on one you need to double it to get the other value. Then divide 90 by 3 to get 30
