2X+3Y=4K+9 (1)
X-2Y=6K+7 (2)
(1)-(2)x2
3Y+4Y=4K+9-12K-14
7Y=-8K-5
Y=-(8K+5)/7
(1)x2+(2)x3
4X+3X=8K+18+18K+21
7X=26K+29
X=(26K+29)/7
X+Y=2004
(26K+29)/7-(8K+5)/7=2004
26K+29-8K-5=2004x7
18K=14004
K=/18
K=778