The total interest charged on Mark's credit card for the month is $41.40, calculated as follows:
1. Daily interest rate: {19.5\%365 \approx 0.000534 \)
2. Interest on oven ($1728 from April 3)**:
1728 \times 0.000534 \times 27 \approx 24.95 \]
3. Interest on tires ($1400 from April 8)**:
1400 \times 0.000534 \times 22 \approx 16.45
**Total interest**:
\[ 24.95 + 16.45 = 41.40 \]