1. **State the problem:** Calculate the digoxin clearance for Mrs A, who has congestive heart failure. 2. **Given data:** - Weight = 70 kg - Creatinine clearance (Clcr) = 25 mL/min - Condition: congestive heart failure 3. **Formula for digoxin clearance in congestive heart failure:** $$\text{Digoxin clearance} = (0.33 \times \text{weight}) + (0.9 \times \text{Clcr})$$ 4. **Substitute the values:** $$= (0.33 \times 70) + (0.9 \times 25)$$ 5. **Calculate each term:** $$0.33 \times 70 = 23.1$$ $$0.9 \times 25 = 22.5$$ 6. **Sum the terms:** $$23.1 + 22.5 = 45.6$$ 7. **Final answer:** The estimated digoxin clearance for Mrs A is **45.6 mL/min**.