1. There are three radii present in this problem. Of that the diamter is supposedly 42.2 units. Given that the radii should be ⇒ 42.2 / 2 ⇒ 21.2 units
2. With that being said the 3rd radii contains parts x and 10.6. By radii congruency, the length of all radii should be the same, so this 3rd radii should = 21.2 units as well. If so, by the Partition Postulate 21.2 = x + 10.6