Question

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Explanation:

Step1: Define initial depth

The diver starts at 68 feet below sea level, so initial depth \( d_1 = -68 \) (negative for below sea level) or we can think in terms of distance: depth is 68 feet, then ascends 29 feet. Let the remaining depth needed to reach sea level be \( x \).

Step2: Set up equation

After ascending 29 feet, the depth is \( 68 - 29 \). We need to find \( x \) such that \( 29 + x = 68 \) (since ascending 29 and then \( x \) more brings to sea level). Solving for \( x \): \( x = 68 - 29 \).

Step3: Calculate

\( 68 - 29 = 39 \). So the diver needs to ascend 39 feet (a change of +39 feet in depth, or a depth change of 39 feet upward) to reach sea level.

Answer:

39 feet