Answer:
30 Days
Explanation:
As provided, we have:
The selling party has clearly mentioned in the sales invoice that warranty period is of 30 days, even though the purchase order demanded warranty of 90 days, but since the buyer accepted the chairs with warranty of 30 days clearly stated, and this acceptance is communicated by the use of chairs by the buyer.
This is clearly acceptance by Extron Inc. as they have used chairs, beyond the warranty period allowed, now there is no warranty available on chairs.
Thus, effective warranty period will be 30 days.