Ivan's house is 3/4 km from school.
3/4 km x 1, 000m / 1km= 3, 000 m/ 4 (the km was cancelled)= 750 m
he had already biked 2/3 of that distance:
750m x 2/3= 500m(the distance he had already biked before the tires went flat.)
What part of a kilometer had he biked?
What part of a kilometer is 500m?
To find the part, we do this:
500m x 1km / 1000m (cancel m)
Therefore, the answer is 1/2 km.