Translation takes place in the what on a what?

Johnny rode his bike to a friend's house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was not able to play. what was his displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point

Wich level of organization includes all the other levels or organizations

Which step is not included in the step approach to calculating the greatest common divisor?