A Woman Walks Due West on the Deck of a Ship

Short Answer

A woman walks due west on the deck of a ship at $6 \mathrm { mi } / \mathrm { h }$ . The ship is moving north at a speed of $20 \mathrm { mi } / \mathrm { h }$ . Find the speed of the woman relative to the surface of the water. Round the result to the nearest tenth.