According to the case

According to the case, Mr. Carter conducted some informal inquiry and made an informal payment structure. Informal structures are easy and less expensive than a formal structure, but they have some problems like sometimes they might be ambiguous and unfair and there might be biases in the payment structure what we can notice in this case.
Regarding these issues, first, we suggest Jennifer conducting a formal inquiry rather than informal and establish an obvious and fair payment structure.
After that, we would suggest not to follow the policy of paying 10% above prevailing rates rather they can offer some incentives to those who are performing better. This system can encourage employee’s loyalty and motivate them to perform better to get more. Most importantly, it would reduce the cost.
Finally, the informal policy of paying men about 20% more than women shows biases. It looks unfair to the women who are doing the same job. In that case. Jennifer can follow a working benchmark during paying her employees. And the incentive system would also work well in this matter.