A wholesale paper company sells a 100-pound package of computer paper that consists of three grades, glossy, semi-gloss, and matte, for printing photographs. Glossy costs $5.80 per pound, semi-gloss costs $4.25 per pound, and matte costs $3.75 per pound. One half of the 100-pound package consists of the two less expensive grades. The cost of the 100-pound package is $487. Set up and solve a system of equations, using matrices, to find the number of pounds of each grade of paper in a 100-pound package. (glossy, semi-gloss, matte)