In a crossing situation, which vessel is required to maintain its course and speed?

Both in the domestic and international guidelines tell that when two power-driven vessels are crossing so as to contain risk of collision, the vessel which has the other on her starboard side (the give-way vessel) must keep out of the way.

If you are the give-way vessel, it is your responsibility to avoid a collision. Normally, this means you must change speed or direction to cross behind the other vessel which is the stand-on vessel.

At evening, when you perceive a red light crossing right-to-left in front of you, you need to change your course. But if you perceive a green light crossing from left-to-right, you are the stand-on vessel, and should maintain course and speed.

The leading situations of collision risk are meeting head-on, overtaking, and crossing. When one of two vessels is to keep out of the way (give-way vessel), the other, the stand-on vessel, must uphold course and speed.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.