Question 64809
Let x=amount of 18% silver
Then 120-x=amount of 54% silver

Now we know that the amount of pure silver in the 18% mixture (.18)(x) plus the amount of pure silver in the 54% mixture (120-x)(.54) must equal the amount of pure silver in the final mixture (120)(.39) so our equation to solve is:


.18x+.54(120-x)=(120)(.39)  simplifying we get:

.18x-.54x+64.8=46.8  collecting like terms we have:

-.36x=-64.8+46.8=-18
x=50 grams of 18% silver

and 120-x=120-50 =70 grams of 54% silver

ck
70(.54)+50(.18)=120(.39)
37.8+9=46.8
46.8=46.8

Hope this helps.  Happy holidays.----ptaylor