hello, please help me i don't know how to answer this question. The answers down below(100g of 18-carat gold and 50 g of 9-carat gold)but I just don't know how to get it ?to the answer by using system of equation ?

1 1. Pure, or 24-carat, gold is very soft, so it is rarely used to jewellery. Most gold jewellery contains a certain percent of gold, mixed with cheaper metals that make it harder. Suppose a jewellery maker has some 18-carat gold, which contains 75% gold, and some 9-carat gold, which contains 37.5% gold. What mass of each should the jewellery maker melt and mix to make 150 g of 5-carat gold, which contains 62.5% gold? [100 g of 18-carat gold and 50 g of 9-carat gold]