Answer:
12
Step-by-step explanation:
Triangle PQR and triangle STR are congruent and that makes |PR| and |SR| equal in measure:
2x + 6 = 4x export like terms to same side
6 = 4x - 2x subtract
6 = 2x divide both sides by 2
3 = x
SR is represented with 4x now replace x with 3
SR = 4*3 = 12
