All firms are assumed to aim at maximizing profits or minimizing losses. The monopolist controls his output or price, but not both.
The monopoly maximizes profits where: MR = MC (the necessary condition of profit maximisation)
He cannot produce at less than Qo because MR will be greater than MC. The monopolist will determine his output at Q Xo and set the price at Po and his total Revenue is OQo X OPo and the to total cost will be OCo X bQo and abnormal profits Po CO AB