The journal entries are as follows
In the books of Giles Agency
1. Account receivable  Dr $3,080
       To Service revenue $3,080
(Being the service is provided in account)
The computation is shown below:
= $3,500 - $3,500 × 12%
= $3,500 - $420
= $3,080
2. Account receivable  Dr $700
       To Service revenue $700
(Being the service is provided in account)