we know that the shaded side is 90 degrees and we are given 28 degrees
So we add 90+28 and we get 118
Since a triangle has 180 degrees, we subtract 180-118 to fins the missing angle measure
180-118=62
x=62
Your equation is 180=90+28+x
well it is a right triangle so you know the angle is 90
all angles in a triangle equal 180 degrees
so you make an equation
28+90+x=180
simplify
118+x=180
-118 -118
x=62 degrees
hope I was helpful
