An alloy of silver and gold is to be recast with an addition of silver. the alloy consists of 80 ounces, 10 ounces of which are gold. if the new alloy is to have only one-fifth of an ounce of gold in 5 ounces, how much silver must be added? a.) 170 ounces b.) 77 ounces c.) 4 ounces

An alloy of silver and gold is to be recast with an addition of silver. The alloy
consists of 80 ounces, 10 ounces of which are gold. If the new alloy is to have
only one-fifth of an ounce of gold in 5 ounces, how much silver must be added?
How would you set up the equation?
:
The original 80 oz has 10 oz of gold or 10/80 = .125 (12.5%) gold
:
The resulting amt is to have, .2 oz in 5 oz, or .2/5 = .04 (4%) gold
:
let x = amt of silver to be added
;
Write an "amt of gold" equation:
.125(80) = .04(80+x)
:
10 = 3.2 + .04x
:
10 - 3.2 = .04x
:
6.8 = .04x
;
x = 6.8%2F.04
x = 170 oz of silver required