http://www.mathcenter.net/forum/atta...1&d=1303459174
$3561x +6439y=55756$ --1
$6439x+3561y =44244$ --2
$(1)+(2)$ $10,000(x+y) = 100,000$
$(1)-(2)$ $2878(y-x) = 11512$
$x+y = 10$
$y-x = 4$
$x=3 y = 7$
$2011x+2554y = 2011(x+y)+543y = 20110 + 543(7) = 23911$