Help please and thank you

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

Dna and rna share a number of similarities,but they also differ in certain aspects of their structure. wich nitrogenous base is found in rna but is not found in dna

The wind is to parities grasses because it them