Net working capital is the difference between the Total Current Assets and Total Current Liabilities.
The December 31, 2015, balance sheet of Maria's tennis shop, inc., showed current assets of $1,145 and current liabilities of $935.
Hence, Net working capital as on December 31, 2015 shall be (1145-935) = $210
The December 31, 2016, balance sheet showed current assets of $1,360 and current liabilities of $1,035.
Hence, Net working capital as on December 31, 2016 shall be (1360-1035) = $325
So the change in the net working capital in the year 2016 shall be (325-210)= $115