Which relationship between the two species listed would be mutually beneficial

What types of energy transfers and energy transportations are involved in the domino chain reaction?

An easy way to calculate the amount of energy available at each level is to 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