Windsor's gross profit for the month is:C. $1520.
First step
January purchase:
Purchase= 130 - (210 - 130)
Purchase=130-80
Purchase= 50 units
Sales revenue= (260 + 50) x 9
Sales revenue=310×9
Sales revenue= $2,790
Second step
Cost= (260 x 4) + (50 x 4.60)
Cost=1,040+230
Cost= $1,270
Third step
Gross profit:
Gross profit= 2,790 - 1,270
Gross profit= $1,520
Therefore the correct option is C.
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