Respuesta :

Answer:

x = 21

Step-by-step explanation:

Since SR = ST then the triangle is isosceles with 2 base angles being congruent, so

∠ STR = 5x - 30

∠ STR and ∠ STU are adjacent angles on a straight line and sum to 180° , that is

5x - 30 + 5x = 180

10x - 30 = 180 ( add 30 to both sides )

10x = 210 ( divide both sides by 10 )

x = 21