Zook Incorporated, had net income for 2015 of $4,500,000. Additional information is as follows:

Amortization of patents $ 45,000

Depreciation on plant assets 1,650,000

Long-term debt:

Bond premium amortization 65,000

Interest paid 900,000

Provision for doubtful accounts (both increased):

Current receivables 80,000

Long-term nontrade receivables 30,000

What should be the net cash provided by operating activities in the statement of cash flows for the year ended December 31, 2015, based solely on the above information?

*answer is $6,240,000, I'm just not sure how to get it :))