Weight of the patient last week = 218 pounds
We already know that
1 kg = 0.453592 pounds
Then
218 pounds = 0.453592 * 218 kg
= 98.8831 kg
= 98.88 kg
Weight of the patient now = 98.10 kg
Then
The amount of weight lost by the patient = (98.88 - 98.10) kg
= 0.78 kg
So the patient loses 0.78 kg within a week. I hope the procedure is clear enough for you to understand. Only conversion part is important to take note while getting to the solution.