解: 4/7Ⅹ × 3/4 =7/5Ⅹ - 24/25
3/7Ⅹ=7/5Ⅹ- 24/25
7/5Ⅹ-3/7Ⅹ= - 24/25
(通分) → 49/35Ⅹ-15/35Ⅹ= - 24/25
34/35Ⅹ= - 24/25
Ⅹ= - 84/85
负的八十五分之八十四