Question

How much of an alloy with 30% copper must be added to 25 pounds of a second alloy which is 20% copper to create a 27% copper alloy?

Answer 1

The answer is: 58.33 lb,

There are already 25 lbs of alloy copper, of this 25 lbs 20% is pure copper content.
25(0.5)= 5 lbs

Answer 2

he is right

Answer 3

she*

Answer 4

sorry she

Answer 5

let x pounds of 30 % copper ne added to 25 pounds of 20% copper to form (x+25) pounds of 27% copper.
\[x \times 30 \%+25\times 20 \%=(x+25)\times 27 \% \]
multiply by 100
\[30x+25\times20=27x+25\times27\]
\[30 x-27 x=25\times 27-25\times 20=25\times (27-20)\]
\[3 x=25\times 7=175\]
\[x=\frac{ 175 }{ 3 }\approx 58.33 ~pounds\]