Having a hard time understading this. Explanation is attached. Why does a gain on the sale of land reduce net income? And why is an increase in accounts payable added to net income?

1. A company uses the indirect method to determine its cash flows from operating activities. Use the following information to determine its net cash provided or used by operating activities. Net income Depreciation expense Cash payment on note payable 8,000 Gain on sale of land Increase in inventory Increase in accounts payable 2.850 15,200 10,000 3,000 1,500 a. $23,550 used by operating activities b. $23,550 provided by operating activities c. $15,550 provided by operating activities d. $42,400 provided by operating activities e. $20,850 provided by operating activities