Answer :
normally, length>width
so if it is 9ft in width then
36>18
so
36inches:9ft
divide both sides b 9
4inches:1ft
so the scale factor is 4in:1ft
so if it is 9ft in width then
36>18
so
36inches:9ft
divide both sides b 9
4inches:1ft
so the scale factor is 4in:1ft