<image> As shown in the figure, the equation is a fractional equation, and the Chinese characters in the equation represent numbers taken from 1, 2, 3, 4, 5, 6, 7, 8, 9. Different Chinese characters represent different numbers. If "成功" (success) respectively represents 6 and 1, the question asks: What four-digit number is represented by "业精于勤" (perfection through diligence)? List all possible answers.