Final answer:
To determine the total diving distance for Caroline to reach Anna-Grace, we add Caroline's height above the lake (18 feet) to Anna-Grace's depth below the surface (12 feet), totaling 30 feet.
Step-by-step explanation:
Caroline is standing 18 feet above the lake on a dock, and Anna-Grace is swimming 12 feet below the lake's surface. To find out how far Caroline will dive to reach Anna-Grace, we need to add the distance Caroline is above the water to the distance Anna-Grace is below the surface.
Total diving distance = Distance from dock to water surface + Distance from water surface to Anna-Grace
Total diving distance = 18 feet + 12 feet
Total diving distance = 30 feet
Therefore, Caroline will dive 30 feet to reach Anna-Grace.