I am having trouble understanding how to get B & C. Can you explain it to me?

2. Calculate the amounts paid by the payer and the patient and the amount the provider must write off. The patient undergoes chemical ablation of one facial lesion in her physicians office. The physicians fee is $240. The patients copayment is $18, and the patient is not required to pay any additional amount to the provider. The payer reimburses the physician $105.

a. Enter the amount the patient pays the provider: $

b. Enter the amount the payer reimburses the provider: $

c. Enter the amount the provider writes off the account: