<PRE><B>Question 1027852</B>
 Mixing a given quantity of 30% silver alloy with a quantity of 90% silver yields 200 units of a 54% silver alloy.
 How many units of each alloy were used
:
:
let x = amt of 30% silver alloy 
let y = amt of 90% silver alloy
:
Two equations
x + y = 200
x = (-y+200); we can use this form for substitution
and using the decimal equiv:
.30x + .90y = .54(200)
replace x with (-y+200) 
.30(-y+200) + .90y = .54(200) 
-.30y + 60 + .90y = 108
-.30y + .90y = 108 - 60
.60y = 48
y = 48/.60
y = 80 units of the 90% alloy
then
200 - 80 = 120 units of the 30% alloy
:
:
See if that checks out in the mixture equation
.30(120) + .90(80) = .54(200)
36 + 72 = 108; confirms our solutions


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