Nine Chapters on Mathematical Art, Vol. 1

Multiplying the denominator by the divisor: this refers to when both the divisor and dividend have fractions, so one must have the denominators multiply the whole numbers and add the numerators, and then have the denominators cross-multiply the top and bottom numbers.

Now suppose a field is 4/7 of a bu pace/step wide and 3/5 of a bu long. Question: What is the area of the field?

->Answer: 12/35 of a square bu.-<

Suppose a field is 7/9 of a bu wide and 9/11 of a bu long. Question: What is the area of the field?

->Answer: 7/11 of a square bu.-<

Suppose a field is 4/5 of a bu wide and 5/9 of a bu long. Question: What is the area of the field?