Answer:
x=8
Explanation:
we know that
If Quadrilateral RSTU is a rectangle
then
The measure of angle STU is a right angle
m∠STU=90°
m∠STU=m∠STR+m∠RTU
so
m∠STR+m∠RTU=90° -----> complementary angles
substitute the given values
(3x-2)+(8x+4)=90°
Solve for x
11x+2=90
11x=90-2
11x=88
x=8