Hey!
First, we know that 23 acres of his purchase are reserved for a community center, so we have to subtract that from the total amount.
[tex]435-23=412[/tex]
Now, we divide the result by 4 to see how many four-acre building lots are available for sale.
[tex]412/4=103[/tex]
103 four-acre building lots are available for sale.
Let me know if you have any questions regarding this problem!
Thanks!
-TetraFish