PLEASE HELP!! Will mark brainliest, i’m struggling. Please find PR.

Answer:
PR = 15
Step-by-step explanation:
PR = PQ + QR
10x - 45 = 3 + x + 6 {Combine like terms}
10x - 45 = 9 + x {Subtract 'x' from both sides}
10x - x - 45 = 9
9x - 45 = 9 {Add 45 to both sides}
9x = 9 +45
9x = 54
x = 54/9
x = 6
PR = 10x - 45
= 10*6 - 45
= 60 - 45
PR = 15