(a) If a participant or student breaches the contract with the Office by failing to either begin the service obligation or to complete it, the Office shall be entitled to recover from the individual an amount determined by the following formula, plus interest:

in which “A” is the amount the Office is entitled to recover; “F” is the sum of the amounts paid under this chapter to or on behalf of the individual; “T” is the total number of months in the individual's period of obligated service; and “S” is the number of months of such period already served by the individual. Interest shall be charged on the outstanding principal at the rate of 10 percent per year. Interest shall begin to accrue from the date of the breach, as determined by the Office. Repayment shall be required in quarterly installments, in amounts calculated by the Office to permit repayment in seven years.