Question

Greg’s home is 1.8 miles from his school there is a music store halfway between school and his home today Greg wants to stop at the store after school right now he is 0.36 miles away from school

Answer 1

I'm guessing the question is "how far does he have to walk to the store from where he is"

if he is walking home, then hmm
distance from store to school=1.8/2 since it is halfway, so 0.9 miles

he has walked 0.36 miles
so he needs to walk 0.90-0.36=0.54 miles

he needs to talk 0.54 miles to get to the store