When building a staircase, you need to be concerned with the height of the riser and the depth of tread so that people can go up and down the stairs comfortably. One rule of thumb used to determine proper riser height and tread depth is that the sume of the tread depth (in inches) and twice the riser height (in inches) should equal 26 inches. Write an equation that models this situation. The riser height of a set of steps in 5 inches. What should be depth be?