Answer:
D. 0.925x + 0.88y = 0.91(x + y)
Step-by-step explanation:
The important point to remember is that the total mass of pure silver is the same on each side of the equation.
0.925x = mass of pure silver in first alloy
0.88 y = mass of pure silver in second alloy
The final alloy has a mass of (x + y) g and is 91 % pure silver, so
0.925x + 0.88y = 0.91(x + y)
