Answer: 9.5 feet
Step-by-step explanation: First, add 12.4 + 12.4. This equals 24.8. Next subtract 43.8 - 24.8. This equals 19. Finally, solve 19 divided 2 because it is a rectangle and a rectangle has two sides of the same length/width. 19 divided by 2 is 9.5 feet. I hope this helps!