2. Master Wang needs to process a batch of parts. If he processes 20 parts per day, he can complete the task 1 day ahead of the original plan. After working for 4 days, due to improved technology, he processes 5 more parts per day than before. As a result, he completes the task 3 days ahead of the original plan. How many parts are there in total? (10 points)
Engineering Question:
Technical improvements advanced the schedule by $\quad 3-1=2$ (days),
The work for the last two days is $20 \times 2=40$ (units),
Pushing 5 units per day, it took $\quad 40 \div 5=8$ (days),
Working 20 units per day for 8+4+3-1=14 (days),
This batch of items totals $14 \times 20=280$ (units).