If radii of two concentric circle are 28 cm and 18 cm respectively if the perimeter and the area of the circle are numerically equal then find the radius of the circle

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.