Answer:
If it was likely or probable that the farm co-op would meet the benchmark and get the discount (or rebate), then the journal entry should recognize that. But since it is very doubtful that the benchmark will be met, then the journal entry should be made without considering any type of discount.
I looked for a similar question in order to find the missing numbers:
each trencher is sold at $3,600 and costs $2,000
August 10, 2019, 16 mini trenchers sold to farm co-op
Dr Accounts receivable 57,600
Cr Sales revenue 57,600
Dr Cost of goods sold 32,000
Cr Inventory 32,000