Question 14
The collar - a necklace is composed of large pearls and small pearls, totaling less than 500 pearls. i. If we replace $70\%$ of large pearls with small pearls, the weight of the necklace decreases from $60\%$. II. If we replace $60\%$ of small pearls with large pearls, the weight of the necklace increases from $70\%$. How many pearls does the necklace have?