HALP, plz explain steps,
A metal alloy is a mixture of two or more metals. A jeweler wants to make 8 grams of 18-carat gold, which is 75% gold. The jeweler has an alloy that is 90% gold and an alloy that is 50% gold. How much of each alloy does he use?

please use a system of equations to explain, would help, and maybe use elimination