Answer:
C(L) = 4L + 3600/L (assuming common wall is width)
C(L) = 3L + 4800/L (assuming common wall is length)
Step-by-step explanation:
The area of residence is 1200 sq feet.
LW = 1200
W = 1200/L
The length of one residence is L, and the width is 1200/L.
I assume the common wall is the width.
The total length of the duplex is 2L.
The width is W = 1200/L
Also, the perimeter of the entire duplex is 2L + 2L + W + W.
In addition, there is a common wall whose length is the width of the duplex.
The entire length of cinder block walls is 2L + 2L + W + W + W, but we know that W = 1200/L, so we get
C(L) = 4L + 3W
C(L) = 4L + 3(1200/L)
C(L) = 4L + 3600/L
This is with the assumption that the common wall is a width, not a length.
If the common wall is a length, then we get this.
The perimeter of the entire duplex is L + L + 2W + 2W.
The common wall is a length of the duplex.
The entire length of cinder block walls is L + L + 2W + 2W + L, but we know that W = 1200/L, so we get
C(L) = 3L + 4W
C(L) = 3L + 4(1200/L)
C(L) = 3L + 4800/L
