Brass is made from a mixture of copper and other elements. A mixture that is 80% copper is combined with a mixture that is 60% copper, resulting in 100 pounds of brass that is 65% copper.

Which equation can be used to find x, the amount of 60% mixture used to create the 65% mixture?

0.8(100 – x) + 0.6x = 100(0.65)
0.6(100 – x) + 0.8x = 100(0.65)
0.8(100) + 0.6x = 0.65(100 - x)
0.6(x) + 0.8(100 + x) = 0.65