A scuba diver has a taut rope connecting the dive boat to an anchor on
the ocean floor. The rope is 140 feet long and the water is 40 feet
deep. To the nearest tenth of a foot, how far is the anchor from a point
directly below the boat?

Setup a right triangle with the boat on top. Striaght down is 40 feet. The rope makes the hypotenuse at 140 feet. The floor of the ocean makes the third side.