Question 1196591
A speculator sold some shares of stock worth $2880. Several days later, the stock having dropped in price $2 per share, he repurchased, for the same amount of money, 6 more shares than he sold. How many shares did he sell? 
<pre>Let the number of shares sold be S
Then sale price per share = {{{"2,880"/S}}}
With 6 more shares being repurchased than were sold (S + 6), price per share, upon repurchase = {{{"2,880"/(S + 6)}}}
We then get the following PRICE-PER-SHARE equation: {{{matrix(1,3, "2,880"/S, "=", 2 + "2,880"/(S + 6))}}}
                                                    {{{matrix(1,3, "1,440"/S, "=", 1 + "1,440"/(S + 6))}}} ------ Factoring out GCF, 2, in numerator
                                     {{{matrix(4,3, "1,440"(S + 6), "=", S(S + 6) + 1440S, 1440S + "8,640", "=", S^2 + 6S + 1440S, S^2 + 6S - "8,640", "=", 0, S^2 + 96S - 90S - "8,640", "=", 0)}}}
                                    S(S + 96) - 90(S + 96) = 0
                                                  (S - 90) = 0        or        S + 96 = 0
                              Number of shares sold, or {{{highlight_green(matrix(1,3, S, "=", 90))}}}     or        S = - 96 (ignore)</pre>