Solution: suppose there are x people at first, and then there are (x+5) people.

1 person 1 hour completion 1/80

So x× 2x1/80+(x+5) x8x1/80 = 3/4.

Multiply both sides by 80.

2x+8(x+5)=60

2x+8x+40=60

10x=20

x=2

x+5=7

A: At first, it was two people, and later it was increased to seven people.