Treasure map - Maths problem

Today I did a maths problem about a treasure map, so the captain of the black heart berries have lost the're treasure map and now doesn't know were they put the treasure chest without the treasure map so they have to memorise what the map looked like. So they remembered that there was five rows and three trees running to the east side and four boulders going down the south side so the treasure chest is half way from the boulders.