1)puritatea=masa pura/masa impura * 100=>masa pura = puritatea * masa impura / 100
masa pura Al = 320 * 70/100 = 224 g Al pur
2)puritatea=masa pura/masa impura * 100=>masa pura = puritatea * masa impura / 100
masa pura Mg = 590 * 90 / 100 = 59 * 9 = 531 g Mg pur