On a map, what do a legend (key) and scale you understand?
1. distance only
2. direction and distance
3. symbols and distance
4. symbols and direction

The answer is 3. symbols and distance.

Explanation:

On a map, the legend (key) explains the symbols used and the scale shows the distances represented in the map.  So the answer is 3.

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

b = (5, -4)

answer they showed that organic molecules such as amino acids could be produced from inoragnic molecules;