calculate how many 12 ft lengths can be used in a given perimeter in excel

i wanted to know if anyone can generate a formula that can figure out how many 12 feet lengths can be used in a given perimeter. I.E.; a window is 24″ X 36″, the perimeter is 120 inches. Each trim is 144 inches long, and will be installed around the perimeter of each window. How many trims will i need to complete a job with 47 windows at the same size. Now, keep in mind that if the perimeter is 120″, i have 24″ left in the first trim that i can still use, and i will use less on the second trim to finish the second window. I’ve been trying for so long, but with no success. Thanks in advance.