From A Treatise of Practical Arithmetic and Book-Keeping, by Single Entry by William Tinwell (Newcastle: William Tinwell, 1805), page 55:

9. Suppose 12 men can mow 49 acres of meadow in 4 days; how many acres will 18 men mow in 22 days?

ans. 404 1/4.

[I found this while searching for lyrics, but then the thought occurred to me: I suppose problems like this were common in the agrarian economy. Is it possible the song began as a parody of an arithmetic problem?]