Original question: Watermelon business owners buy a batch of small watermelons at the price of 2 yuan per kilogram and sell them at the price of 3 yuan per kilogram, which can sell 200 kilograms every day. In order to promote sales, the marketer decided to reduce the price. After investigation, it is found that this kind of small watermelon can sell 40 kilograms per kilogram for every price reduction of 0. 1 yuan. In addition, the daily rent and other fixed costs in 24 yuan. Enterprises mainly want to make a profit in 200 yuan every day. How much should the price of small watermelons be reduced per catty?

If the price is reduced by one yuan, it will be sold at 40× (a/0.1) = 400 Jin.

(3-a)×(200+400 a)-(400 a+200)×2-24 = 200

600-200a+ 1200a-400a？ -800a-400-24-200=0

400a？ -200a+24=0

50a？ -25a+3=0

(5a- 1)( 10a-3)=0

A= 1/5 or a=3/ 10.

Therefore, if the price is reduced to 1/5=0.2 yuan or 3/ 10=0.3 yuan, the profits of 200 yuan can be obtained.

If I can help you, (adopted in the upper right corner)