We know that Angle Bisector Divides an Angle into Two Equal Angles.
As UP is the Angle Bisector of Angle U, It Divides Angle U into two Equal Parts they are Angle(1) and Angle(2)
⇒ Angle(1) = Angle(2)
Given Angle(1) = 5x + 10 and Angle(2) = 3x + 14
⇒ 5x + 10 = 3x + 14
⇒ 2x = 4
⇒ x = 2
⇒ Angle(1) = 5x + 10 = 5(2) + 10 = 10 + 10 = 20
So : Measure of Angle(1) is 20