Answer to Question #210452 in Algebra for khosa

Question

 a chess boared has 64 squares, 32 black and 32 white.at one stage of a chess match, after some pieces has been <b><i>removed</i></b> from the board, there are four more black vacant squares than white vacant squares. the next four moves involves four pieces being moved from black squares to white vacant squares, making the number of black vacant squares now double than of the number of white vacant squares.(No of pieces are now taken off the boared or swopped with other pieces during this process-simply moved from one vacant square to another). create an equation and then solve this equation to determine how many black vacant squares there were before the four picieces where moved.