What major problem did the earliest settlers of Amsterdam encounter? How did they solve the problem?

The biggest problems they had to face were themselves. They had to face the fear of being in a new place, the fear of failure which could result in their deaths. They faced their other characteristics as well, when they finally were able to settle and became confident they then faced their ego.

your answer is b hope that

reflecting point a across the origin negates both of its coordinates.

b = (5, -4)