How is this incorrect?

Effect of Omitting Adjustments For the year ending August 31, Mammalia Medical Co. mistakenly omitted adjusting entries for (1) depreciation of $7,500, (2) fees earned that were not billed of $11,800, and (3) accrued wages of $3,900. Indicate the effect of the errors on (a) revenues, (b) expenses, and (c) net income for the year ended August 31. (a) Revenues understated 11,400 (b) Expenses overstated 11,800 (c) Net income understated 8,200