Answer:
The journal entries are as follows:
1. Cash A/c Dr. $3,500
To Unearned revenue $3,500
(To record gift cards sold)
2. Unearned revenue A/c Dr. $728
To Sales tax payable A/c $28
To sales revenue $700
(To record gift cards redeemed)
Note : The $728 includes a 4% sales tax of $28.