Please answer the math application questions of grade 2 in detail, thank you! (6 21:14:30) Yang Hui, a mathematician in the Southern Song Dynasty, once put forward such a question: "the area of Zhitian (rectangle) is 864 (square steps), only the width (width) of cloud is less than 12 steps (width is 12 steps less than length). How many steps are the length of the problem and its specific solving process

Please answer the math application questions of grade 2 in detail, thank you! (6 21:14:30) Yang Hui, a mathematician in the Southern Song Dynasty, once put forward such a question: "the area of Zhitian (rectangle) is 864 (square steps), only the width (width) of cloud is less than 12 steps (width is 12 steps less than length). How many steps are the length of the problem and its specific solving process

The length is 12 steps more than the width
x(x-12)=864,
The solution is x = 36, X-12 = 24