Nine Chapters on Mathematical Art, Vol. 1

We have entered into the sections of the classic. Thus, multiplying the numerators to form the dividend is like equalizing the gold. Multiplying the denominators to form the divisor is like equalizing the people. Making the denominators the same to be twenty horses serves no purpose, as one only desires to achieve equality. Furthermore, if one horse is worth 3 jin of gold, in a complete rate, speaking in terms of parts, if a person sells 4/7 of a horse, the numerators and the people interact to produce the result. Although the ways of stating them differ, the calculation is the same as the three methods that lead to the same destination.

Now there is a field, 3 and 1/3 bu paces wide, and 5 and 2/5 bu long. Ask: What is the area of the field?

There is another field, 7 and 3/4 bu wide, and 15 and 5/9 bu long. Ask: What is the area of the field?