Among three numbers, the first is twice the second and thrice the third, If the average of three numbers is 517, then what is the difference between the first and the third number?
PQ is a diameter of a circle with centre O. RS is a chord parallel to PQ subtends an angle of 40° at the centre of the circle. If PR and QS are produced to meet at T, then what will be the measure (in degrees) of ∠PTQ?