Luis walked one-eighth of the distance to school. what part of distance to school does he still need to walk?

Total Distance = x
Luis walked one-eighth of x = x(1/8) = x/8 
He still need to walk = Total Distance - Distance covered
He still need to walk = x-x/8
He still need to walk = (8x-x)/8

He still need to walk = 7x/8
He still need to walk = x(7/8) 
He still need to walk seven-eighth of the total distance.