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