Sweeney & Allen, a large marketing firm, adjusts its accounts at the end of each month. The following information is available for the year ending December $31.$

A bank loan had been obtained on December $1.$ Accrued interest on the loan at December $31$ amounts to $$1,110.$ No interest expense has yet been recorded.

Depreciation of the firm$$s office building is based on an estimated life of $30$ years. The building was purchased four years ago for $$310,000.$

Accrued, but unbilled, revenue during December amounts to $$63,000.$

On March $1,$ the firm paid $$1,700$ to renew a $12-$month insurance policy. The entire amount was recorded as Prepaid Insurance.

The firm received $$15,000$ from King Biscuit Company in advance of developing a six$-$month marketing campaign. The entire amount was initially recorded as Unearned Revenue. At December $31,$ $$2,800$ had actually been earned by the firm.

The company$$s policy is to pay its employees every Friday. Since December $31$ fell on a Wednesday, there was an accrued liability for salaries amounting to $$2,400.$

a$.$ Record the necessary adjusting journal entries on December $31.$

b$.$ By how much did Sweeney & Allen$$s net income increase or decrease as a result of the adjusting entries performed in part a$?($Ignore income taxes.$)$