a polymer blend containing 60% PE,50%PP, 30%PVC for industrial use. The available materials in stock are X(containing 25%PE,40%PP and 35%PVC), Y(containing 35%PE, 45%PP, 20% PVC), Z(containing 55%PE, 5%PP, 40%PVC). what amount of x,y and z should be blend to together to produce 100kg of the desired product (use Gaussian elimination method)