7 meters This is just a matter of reading the problem and constructing an expression for it. So let's start. "A scuba diver descends to a depth of 30 meters below sea level" d = 30 "and then rises 23 meters" Since rising is the opposite of descending, will use the opposite sign. Giving: d = 30 - 23 Solve for d d = 30 - 23 = 7 So the diver is 7 meters below the surface when he studies the fish. Assuming the fish are at the same depth as the diver, then the fish are also 7 meters below the surface.