Question

The Smiths want to replace the stairway that leads from their porch to their sidewalk with a ramp. The porch is 3 feet off the ground. They decide to start the ramp 12 feet away from the base of the porch to make it convenient to walk up.

Answer 1

Normally  you need   1  foot   run per 1 inch rise  so to rise   36"  you need a   36  foot ramp.   If you  want to start the  ramp  12 feet from the   porch you will  need to  do a switch back  -- that is,  zig  zag the ramp so as to get 36 feet in  length.

Answer 2

a²+b²=c²

3²+12²=c²

3²=9

12²=144

√153

12.36931688 or 12.4

hope this helps