For the seventh grade mathematics of compulsory education, the first volume 106, pages 3, 4 and 5, review and consolidate the equation in one yuan at a time.
Solution: Assuming that the original X people do it, the efficiency is 1/80.
1/80x * 2+(x+5)1/80 * 8 = 3/4 (unit1is a batch of data).
1/40x+ 1/40x=3/4
x= 15
15+5=20 (person)
Just arrange 20 people directly.