A circle has points P, Q, R on a circle in such a way that angle PQR is 60 deg and angle QRP is 80 deg. Calculate the angle subtended by an arc QR at the centre.
Atul and Binay together complete a piece of work in 5 days. If Binay alone can complete the same work in 8 days, how many days Atul take to complete the same work alone?