Answer:
35
Step-by-step explanation:
Answer:
58.33 lbs.
Step-by-step explanation:
There are already 25 lbs of alloy of copper
Of this 25 lbs, 20% is pure i.e. copper content = 25(0.5) = 5lbs.
Now available is
Copper Other metals
5 lbs 20 lbs
Let x lb of 30% copper is added.
Then new alloy will have 5+0.3x lb copper in total of 25+x lbs
Percentage pure = 
Simplify to get

Hence answer is 58.33 lbs should be added.
Answer:
x = 15
Step-by-step explanation:
hope this helps, have a great day/night!!
Answer:
Infinite solutions
Step-by-step explanation:
So if simplified it would be
-3x+15=15-3x
Which is basically the same thing if arranged
15-3x=15-3x
-3x+15 can also be 15-3x still the same thing as adding 15 to -3x
So since these are equal anything could be used
like try 0
Both get 15
Try 1
Both get 12
Try legit any number
youll get the same results (I would choose 3 positive easy ones, 0,1,2 and 3 negative ones -1,-2,-3)