Apharmaceutical company sells bottles of 500 calcium tablets in two dosages: 250 milligram and 500 milligram. last month, the company sold 2,200 bottles of 250-milligram tablets and 1,800 bottles of 500-milligram tablets. the total sales revenue was $39,200. the sales team has targeted sales of $44,000 for this month, to be achieved by selling of 2,200 bottles of each dosage. assume that the prices of the 250-milligram and 500-milligram bottles remain the same.
determine the price of a 250-milligram bottle as well as the price of a 500-milligram bottle.

Let x and y be the prices of the 250 milligram and 500 milligram dosage, respectively. The equations that may be derived from the given conditions above are,
                                   2200x + 1800y = 39200
                                   2200x + 2200y = 44000
Solving the system by subtracting the second equation from the first gives,
                                         -400y = -4800   ; y = 12
Substitute the obtained value for y in either of the equations. I choose the first equation,
                                  2200x + (1800)(12) = 39200
                                           2200x = 17600    ;    x = 8
Thus, the 250-mg bottle costs $8 and each 500-mg bottle costs $12.