Help. I don't get it. Ugh...

Question

Hilary was scuba diving. She was 30 feet below the surface when she swam toward the dive platform. She dropped her camera when she was 10 feet from the surface and had to swim down 15 feet to get it. At what elevation did Hilary retrieve her camera? 

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 feet

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 feet

Answer 1

She was underwater, so elevation is negative. The deeper she dives the more negative is her elevation.

She started out at -30 feet. When she dropped her camera, she was at -10, so she had swum 20 feet up to the surface. She then had to go back down 15 feet to get the camera, so she went down another 15 feet below 10 feet, which is 25 feet below or -25 feet, third answer.