If the surface of the water is at an elevation 0 meters, which person is located at an elevation of -10 meters?
Noa, who is floating on his back in the water 10 meters behind a boat
Jace, who is exploring a cave that is 10 meters below the surface of the water
Marcus, who is swimming 10 meters below a bird flying overhead
Eleni, who is standing on a pier 10 meters above the surface of the water

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.