13.074. A sewing workshop received three stacks of bed linen material, totaling 5000 m. In the first stack, the amount of material was three times less than in the second, and in the third - $22 \%$ of the total amount. From the material of the first stack, 150 sheets and 240 pillowcases were sewn. For the production of one sheet, 3.25 m more material was required than for the production of one pillowcase. How many meters of material are used to sew one pillowcase?
Solution.

Let $x$ m of material be in the first bale, $3 x$ m - in the second, $5000 \cdot 0.22=1100$ m - in the third. According to the condition, $x+3 x+1100=5000$, from which $x=975$ m - in the first bale. Let one pillowcase be sewn from $y$ m of material, and a sheet - from $3.25+y$ m. A total of $(3.25+y) \cdot 150$ m of material was used for the sheets, and $240 y$ m for the pillowcases. According to the condition, $150(3.25+y)+240 y=975$, from which $y=1.25$.

Answer: 1.25 m.