Answer: Let the distance be x kilometers.

It is known that the walking speed is 5 km/h and the cycling speed is 4 times that of walking, so the cycling speed is 20 km/h.

According to the two schemes, the time is equal, and the equation can be expressed by time = distance/speed.

(3*2+X)/(5*4)=X/4

Get X=2.

So the community is 2 kilometers away from the library.