The wall will be ##2 1/2## inches long on the drawing
Using ratio:
Write 0.5 inches to 6 feet as:
## 0.5/6##
Let the unknown scale down size be ##x##
Then we have:
## color(brown)(0.5/6=x/30)##
To get ##x## on its own multiply both sides by 30
##color(brown)(0.5/6=x/30) -> color(brown)(color(blue)(30xx)0.5/6 = (color(blue)(30))/30 xx x)##
But ##30/30=1##
## (30xx0.5)/6=1xx x##
## x=2 1/2##