Answer:
Length: 15 inches
Width: 3 inches
Explanation:
Let'
L ----> the length of the model in inches
W ---> the width of the model in inches
we know that
The area of the model is given by the formula

we have

so
----> equation A
Remember that
the width is 12 inches less than the length
so
---> equation B
substitute equation B in equation A

solve for L


Solve the quadratic equation by graphing
using a graphing tool
The solution is L=15 in
see the attached figure
Find the value of W

substitute the value of L

therefore
The dimensions of the model are
Length: 15 inches
Width: 3 inches