Carla and Rob left a 15% tip after having lunch at a restaurant. The amount of the tip was $3. Carla’s lunch cost $12. Write an equation you can use to find x, the cost of Rob’s lunch.

Adolphin is swimming with her friend. the dolphin jumps to a height of 4.54.54, point, 5 meters above the surface of the water as her friend swims 9.89.89, point, 8 meters directly below her. what is the position of the dolphin's friend relative to the surface of the water? meters