Answer:
x = 9
Explanation:
Since the arc AC is congruent to arc BC, we know that side AB is also congruent to side BC.
Therefore, we can construct an equation that equates their side lengths, and then solve for x.
5x + 8 = 53
↓ subtract 8 from both sides
5x = 53 - 8
5x = 45
↓ divide both sides by 5
x = 9