A dolphin went 15 feet below sea level to catch a fish. A shark went twice as deep, then swam down an additional 10 feet to catch a larger fish. Which expression represents the shark’s position in relation to sea level?

Below sea level is represented by a negative number, so the dolphin’s position is −15 feet. The shark went twice as deep: 2 × (−15) = −30 feet, then swam down 10 more feet, represented by adding −10. Thus the expression is 2 times negative 15 plus negative 10, choice C.

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