Hint: The angle of dip is the angle made by the Earth's magnetic field with the horizontal plane.
Step 1: P is in the plane S, the needle is in the north, so the declination is zero.
Step 2: P is also on the magnetic equator, so the angle of dip = 0, because the value of the angle of dip at the equator is zero. Q is also on the magnetic equator, thus the angle of dip is zero.
As earth tilted on its axis by 11.3, thus the declination at Q is 11.3.
