Note that angle r and angle t encompass the entire 360 degree circumference
remember that inscribed angles inercept arcs 2 times the angle
so [ 3x +5 + 5x +15 ] * 2 = 360 now you can solve for x and can label three of the angles
Then ...all of the angles sum to 360 degrees
can you solve for q now ?
All you need to know is that
Opposite angles in a cyclic quad are supplementary.