Solve 3 a. i and ii
and 3 b. i and ii

For 3a, we see that it states that the submarine is 800 feet below sea level. Since it is below sea level, it is negative (as sea level is 0) and therefore -800, making ii correct.

For 3b, since the elevation is -150 feet, and negative means below sea level, the reef is 150 feet below sea level, making i correct.

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