Solution :
1st June : No entry -- neither party has performed under any the contract.
On 1st Sept. 2020
Windows = $ 1,980
Installation = $ 600
Total = $ 2,580
Allocation :
Windows
= $ 1,749
Installation
= $ 530
Revenue recognized = $ 1,749 + $ 530
= $ 2,279
To record sales
Cash = $ 1,980
Account receivable = $ 299