{0,25x+0,40y=1260 {x+y=4050

{0,25x+0,40y=1260 / *100 {x+y=4050 {25x+40y=126000 {x+y=4050 x+y=4050 x=4050-y 25(4050-y)+40y=126000 101250-25y+40y=126000 -25y+40y=126000-101250 15y=24750 /:15 y=1650 x=4050-1650 x=2400 {x=2400 {y=1650

{0,25x+0,4y=1260//*(-2) {x+y=4050 {-x+(-0,8)=-2520 +{ x+y=4050 = 0,2y=1530// ,2 y=306