The houses can be placed in 362,880 ways.
Step-by-step explanation:
The 9 houses are each in different design.
The each lot can place any of the 9 houses.
Similarly, the process gets repeated until the last house is placed on a lot.
From the above steps, it can be determined that :
The number of ways to place the 9 houses in 9 lots = 9!
⇒ 9×8×7×6×5×4×3×2×1
⇒ 362880 ways.
Therefore, the houses can be placed in 362880 ways.