Systematic Treatise on Arithmetic

A: 3 mace, 6 fen, 5 li. The "mutual harmony" An arithmetic mean calculation of A and E together yields 6 mace; halving this yields C: 3 mace. Combining the mean and A’s 3 mace, 6 fen, 5 li yields 6 mace, 6 fen, 5 li; halving this yields B’s silver: 3 mace, 3 fen, 2 li, 5 hao. Combining C and E yields a total of 5 mace, 3 fen, 5 li; halving this yields D: 2 mace, 6 fen, 7 li, 5 hao. This matches the inquiry.

West River Moon

original: 西江月 (Xījiāng Yuè). A rhythmic poetic form used here to frame a word problem.

A flock of sheep, one hundred and forty, sheared with diligent care.
Among them are mothers and lambs.
First, shear two sheep to compare:
the large sheep yields one jin and two taels of wool;
the total wool gathered is one hundred and fifty jin—this is the root of the matter.
How many of each, mother and child, should there be?
Units of weight: 1 jin (斤, "catty") equals 16 liang (兩, "taels").

The Answer says: 120 large sheep and 20 small sheep.

The Method says: Set the number of sheep as 140. Take the wool from the large sheep, 1 jin and 2 taels, and 加六: "add six," a computational shortcut on the abacus for multiplying by 16 to convert jin to taels to get 18 taels. Multiply this [by the 140 sheep] to get 2,520. Subtract from this the total sheared wool of 150 jin, which likewise by adding six becomes 2,400 taels, leaving a remainder of 120.

The marginalia appear to be scribbled calculations or memory aids for the 16-to-1 conversion ratio used in the abacus "add six" method.