0.1 x +15 -0.5x =8.2
-0.4x = -6.8
x =17有1角和5角组成的30枚硬币，共值8元2角，俩种硬币各有多少？设有1角的x 个 5角的 30-x 个0.1 x + 0.5(30-x) =8.2x =17 30-x =131角的17个 5角的13个0.1 x + 0.5(30-x) =8.2具体怎么解啊先去括号 0.1 x +15 -0.5x =8.2然后移项 合并同类项-0.4x = -6.8