To solve this problem, we can break it down into a few steps. First, let's find the original number of staff in Banks D and F, and then we can calculate the number of staff hired by each bank. After that, we can determine the number of staff retrenched from each bank. Finally, we'll compare the retrenchment percentages for Banks D and F.

Let's assume the original staff strength for both banks is S.

1. Staff hired:

   • Bank D hired 15% more than its requirement, so the number of staff hired by Bank D is 1.15S.
   • Similarly, the number of staff hired by Bank F is also 1.15S.

2. Total staff after one year:

   • The total staff strength after one year for both banks is 2.3S (original strength + 15% more).

3. Staff retrenched:

   • The number of staff to be retrenched from the total staff after one year to bring it back to the original strength is 2.3S - S = 1.3S.

Now we can calculate the percentage of retrenchment for Banks D and F:

4. Retrenchment percentage:
   • Retrenchment percentage for Bank D = (Staff retrenched by Bank D / Total staff after one year from Bank D) * 100
   • Retrenchment percentage for Bank F = (Staff retrenched by Bank F / Total staff after one year from Bank F) * 100

Once these percentages are calculated, we can compare them to determine by what percent the retrenchment is less/more in Bank D than in Bank F.

Let's perform the calculations to find the exact percentages.