What is the scale factor of a drawing if the scale is 1 inch =4 feet

 48 is the scale factor!

1 foot = 12

4 feet = 48 inches

1 in. to 4 feet(or 48 in.) = 48 scale factor!

Other examples:

1:   scale factor of 2 in = 4 in = scale factor of 2

2:   scale factor of 20 mm = 8 cm = scale factor of 4

3:   scale factor of 3 ft = 5 m = scale factor of 5

Hope this helps!

if x = 1, then the answer is 3.5