How's is the grouping of stars in a constellation different from the grouping of planets in the solar system

Grouping of stars in constellations is completely arbitrary as it depends solely on our point of view (stars in particular constellation aren't really near together and can be separated by great distances - in fact stars belonging to two different constellations may be closer together than stars in just one of them) and was influenced by our mythological views.
grouping of planets in a solar system at least has an actual basis: planets are  gravitational  bound to a star and are located nearby. hope this !

I assume you mean 20 m/s.

In the first 0.80 seconds, the car travels:

20*0.80 = 16 m

During the period of deceleration, you can calculate the distance travelled using:

where s is the distance travelled, v is the final speed (0), u is the initial speed (20 m/s), and a is the acceleration (-7.0 m/s^2).

This gives:

2*7.0s = 20^2
14.0s = 400
s = 400/14 m

The total distance the car travels is:

16 + 400/14 = 44.6 m (3 s.f.)