How do you make a set of steps for a stage set easily moved 75 plywood spec is 3 steps at an overall height of 29 by 24w and how do you figure out the size of the riser and treads?

your normal rise is 7" and normal tread run 10".If you total rise is 29"than divide that by 7 which is 1" extra so to make it simple each riser would be7 1/4 "