On December $1,$ Vincent Nguyen opened a speech and hearing clinic. During December, his firm had the following transactions involving revenue and expenses.

Paid $$3,100$ for advertising.

Provided services for $$10,400$ in cash.

Paid $$960$ for telephone service.

Paid salaries of $$2,600$ to employees.

Provided services for $$3,000$ on credit.

Paid $$900$ for office cleaning service.

Did the firm earn a net income or incur a net loss for the period? What was the amount?