10%X+8%Y=4400 (1)
8%X+10%Y=4400+200 (2)
(2)公式-(1)
2%Y-2%X=200
Y-X=10000
Y=10000+X (3)
代入(1)
10% X+8% *(10000+X)= 4400
18%x=4400-800
x=20000
代入等式(3)
y=10000+20000=30000