Question 115147
WHAT YOU HAVE IS A RIGHT TRIANGLE WITH A SIDE=9 FEET AND A SLOPE OF 3/4.
THUS YOU HAVE 3/4=9/X OR 3X=36 OR X=36/3 OR X=12 FOR THE SECONF SIDE OF THE RIGHT TRIANGLE.
12 FEET=144 INCHES. WITH A TREAD LENGTH OF 10 INCHES THERE IS ONLY ROOM FOR 
144/10=14.4 STEPS. 
SO TO KEEP WITHIN THE 3/4 SLOPE RESTRICTION YOU CAN ONLY HAVE 14 STEPS.
THE 9 FEET HEIGHT=108 INCHES.
108/14~7.7 INCH RISERS FOR THE 14 STEPS.