What must be the balancing item

Question

Problem: Abbreviated financial statements for Archimedes Levers are shown in  table below. If sales increase by 10% in 2011 and all other items, including debt, increase correspondingly, what must be the balancing item? What will be its value?

Income Statement

Sales                              $4000
Costs, including interest     3500
Net income                       $500

Balance Sheet, Year-End 2010

                   2010         2009                            2010        2009
Assets         $3,200      $2,700      Debt          $1,200       $1,033
                                                     Equity         2000        1667
Total              3200       2700          Total           3200         2700