The surface area of a rectangular box can be found by adding the area of each face:
2lw + 2lh + 2wh = 606
where l is the length, w is the width, and h is the height.
Given that the length is 15 ft and the width is 9 ft, we can substitute these values into the equation:
2 * 15 * 9 + 2 * 15 * h + 2 * 9 * h = 606
270 + 30h + 18h = 606
48h = 336
Dividing both sides of the equation by 48:
h = 7
So the height of the box is 7 ft.