Helppp meeee with thisss for a thanksss

The purple arc is 315 degrees. The remaining bit (angle b) must add to 315 to get 360 degrees, which is a full rotation.
315+b = 360
b = 360-315
b = 45
Answer:
45
Step-by-step explanation:
360-315
its a circle...which means it has a 360 degree angle.