Ax+6=15 a is a negative, what must be true about x?

Ben and cam are scuba diving. ben is 15.815.8 meters below the surface of the water. cam is 4.24.2 meters above ben. what is cam's position relative to the surface of the water? choose 1 choose 1 (choice a) a 11.611.6 meters above the surface of the water (choice b) b 11.611.6 meters below the surface of the water (choice c) c 2020 meters above the surface of the water (choice d) d 20 meters below the surface of the water