The correct way to do it is to make use of angle PQR.

From the properties of angles within a circle, we know that angle 2PQR = angle ROP

Therefore, angle PQR = 110/2 = 55

Now, from quadrilaterals inscribed within a circle, the sum of two opposite angles = 180 degrees.

Therefore, 180 - 55 = RSP

And RSP = 125 degrees