6. Brandon and Marta are mowing a lawn. For every 4 square feet that Brandon mows Marta mows 9 square feet. The lawn is 5200 square feet. How much lawn does $+x$ each person mow?

Step 1 ：Find the ratio of the lawn mowed by Brandon and Marta: \(\frac{4}{9}\)

Step 2 ：Calculate the combined ratio: \(4 + 9 = 13\)

Step 3 ：Find the amount of lawn mowed by Brandon: \(\frac{4}{13} \times 5200 = 1600\)

Step 4 ：Find the amount of lawn mowed by Marta: \(\frac{9}{13} \times 5200 = 3600\)

Step 5 ：\boxed{\text{Final Answer: Brandon mows 1600 square feet and Marta mows 3600 square feet.}}