(1)0.5x-0.2y=200两边同乘以3得: 1.5x-0.6y=600 0.4x+0.6y=1300 两式相加得1.9x=1900 x=1000 y=1500 (2)4X+6Y=29 两边同乘以3得: 12x+18y=87 12X+10Y=75 两式相减得:8y=12 y=3/2 x=5