China Naming Network - Ziwei Dou Shu - A rope is 4/5 meters long, cut 2/5 meters, and cut () meters. A rope is 4/5 meters long. After cutting off some, there are 2/5 left. How much was cut?
A rope is 4/5 meters long, cut 2/5 meters, and cut () meters. A rope is 4/5 meters long. After cutting off some, there are 2/5 left. How much was cut?
Solution: A rope is 4/5 meters long, cut 2/5 meters and cut (2/5) meters.
Subtract 2/5 from this rope, leaving: 4/5× (1-2/5) =12/25 (meters).
This rope, after subtracting some, leaves 2/5, which is 4/5× (1-2/5) =12/25 (m).
This rope is 4/5 meters long. Cut off 2/5 meters, leaving 4/5-2/5=2/5 (meters).