Two particles, each of mass 2.90 x 10-4 kg and speed 5.46 m/s, travel in opposite directions

Question:

Two particles, each of mass 2.90 x 10-4 kg and speed 5.46 m/s, travel in opposite directions along parallel lines separated by 4.20 cm.
(a) What is the magnitude L of the angular momentum of the two-particle system around a point midway between the two lines?
(b) Does the value of L change if the point about which it is calculated is not midway between the lines? If the direction of travel for one of the particles is reversed, what would be?
(c) The answer to part (a) and
(d) The answer to part (b)