Repaired: Remaining =2:3
Repair 80 * 2/(2+3) = 32m.
2. A rope was cut off by 20% and then connected to 5 meters, which was three twentieth shorter than the original one. How many meters is it now?
5/(20%-3/20)= 100 meter
3. To repair the expressway, it is planned to repair1.24m every day, which is 0.2km less than the actual daily repair. What is the total length of this highway?
Answer: Build 0.2 km more, and actually finish the expressway five days ahead of schedule.
Original plan 1.24*5/0.2=3 1 day.
The total length is 31*1.24 = 38.44m.
B: It's 0.2 kilometers short. Actually, it's five days later than the scheduled time to finish the expressway.
Originally planned (1.24-0.2)*5/0.2=26 days.
The total length is 26 * 1.24 = 32.44 meters.