Help me with this geometry problem

An architect wishes to represent the length of a room with a 5 inch segment.

1. If the room is actually 18 feet long,'write the ratio of the scale length to the actual length.

The answer to this is 5/216
Below is the problem I need help on.

2. Find the scale width, if the room is 12 feet wide.

Please solve and explain how to get the answer. Thanks in advance!

5/216 = x/144
(5)(144)/216 = x
10/3 inches = x
Or 3 and 1/3 in = x
Or 3.333in = x

Assuming the scale is the same ; that is representing an 18 foot room with a 5 inch segment. The 12 foot room has a scale width of 3.33 inches.
This is calculated by knowing the 18 foot room is represented by a scale of 5 inches. The question is then asked "What is the length of scale to represent a 12 foot room?". will the answer be more or less then 5 inches. The answer is "less" because 12 feet is less than 18 feet.
You then place 12 over 18 and multiply by the scale length of 5 inches as follows:
(12/18) x 5 = 3.33 inches. You could convert all the calculation to inches but the result is the same:
(144/216) x 5 = 3.33. Hope this helps

5 inches = 18 feet
or
5 inches= 216 inches
if the room is 12 feet, then convert to inches. so 12*`12 =144
set up a proportion.
numerator=scale
denominator= actual
5/26=x/144
and should be basic from here