pay a debt; meet one's engagements
償還債務

serve one's debt
償還貸款

pay back the exact amount
如數償還

bad pay
沒有償還能力

good pay
有償還能力

repay a hundred-fold
百倍償還

They are under to obligation to repay debts incurred by the old regime.
他們沒有償還舊債的義務。