Vario was scuba diving at an elevation of −20 feet and then descended 20 feet more. Dario and another person scuba diving. The other person is diving at negative thirty feet.

A number line from negative fifty to fifty by tens is shown.

After the descent, what was his elevation in relation to another diver at an elevation of −30 feet?

Enter the correct answers in the boxes.

Equation: $$

Relative elevation:
ft