Fields of Grain

I have two fields of grain.  From the first field I harvest 2/3 sila (a measurement of grain volume) per sar (a unit of area); from the second, 1/2 sila per sar.  The yield of the first field exceeds the second by 500 sila.  The total area of the two fields together is 1800 sar.  What is the area of each field?

VAT 8389 (Mesopotamian tablet), c. 1800 BCE

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