The formula for a persons work speed is s=w-10e/m where s is speed in work per minute w is the amount of work e is the number of errors and m is the number of minutes worked. solve for e

Johnny rode his bike to a friends house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was unable to play. what was his displacement for the total bike ride trip? what could you use as a reference point ? show the steps to solve this problem.