Respuesta :

9514 1404 393

Answer:

  42°

Step-by-step explanation:

The measure of angle PUR is half the sum of the measures of arcs PR and ST.

  ∠PUR = (1/2)(arc PR +arc ST)

Using measures in degrees, we have ...

  81 = (1/2)(PR +120)

  162 = PR +120 . . . . . . multiply by 2

  162 -120 = PR = 42 . . . . subtract 120

The measure of arc PR is 42°.