买了两种面料,共计138m,花了540元,其中蓝布每米3元,黑布每米5元。这两种布料的每种材料多少钱? (540 - 138×3)÷(5 - 3)= 126 ÷ 2= 63m黑布63 × 5 = 315元138-63 = 75m蓝布75× 3 = 225元