Sea turtles are among the most ancient creatures on Earth. There are seven species of them today and they all have existed for 1
10 million years (since dinosaurs roamed on the planet!) Sea turtles eat a wide range of animals and plants. John also loves sea turtles. He plans to cover a wall with 4 posters of sea turtles all in a row. His wall is 18 feet high and 24 feet wide. If the height of a poster is not greater than two times the width, what is the maximum height of a poster?