Question 1158751
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I will solve only one problem for you.


2. Mixture Problem
How much water must be evaporated from 80 pounds of a 12% solution of salt in order to obtain a 20% solution?


<pre>

Let W be the MASS of water to evaporate, in pounds.


The amount of salt in the original 80 pounds of the 12% solution was  0.12*80 = 9.6 pounds.


When W pounds of water were evaporated, the remaining mass became  80 pounds - W pounds.


We want the new salt concentration be 20%.  It means

    {{{9.6/(80 - W)}}} = 0.2.   (1)


(Notice that when the water evaporates, the mass of salt REMAINS the SAME (!) )


To solve equation (1), multiply both sides by (80-W).  You will get

    9.6 = 0.2*(80-W).


Simplify and find W.

    9.6 = 0.2*80 - 0.2W

    0.2W = 0.2*80 - 9.6 = 6.4,

    W = {{{6.4/0.2}}} = 32 pounds.


<U>ANSWER</U>.  32 pounds of water should be evaporated.


<U>CHECK</U>.  I will check equation  (1) for the concentration

        {{{9.6/(80-32)}}} = {{{9.6/48}}} = 0.2,  which is precisely correct (!)
</pre>

Solved.


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It is a standard and typical mixture problem.


In this site, there is a bunch of lessons, &nbsp;covering various types of mixture problems. &nbsp;See introductory lessons

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Mixture-problems.lesson>Mixture problems</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/More-Mixture-problems.lesson>More Mixture problems</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Solving-typical-mixture-problems.lesson>Solving typical word problems on mixtures for solutions</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-antifreeze-solutions.lesson>Word problems on mixtures for antifreeze solutions</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-alloys.lesson>Word problems on mixtures for alloys</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Typical-word-problems-on-mixtures-from-the-archive.lesson>Typical word problems on mixtures from the archive</A>


Read them and become an expert in solution the mixture word problems.


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this online textbook under the topic "<U>Mixture problems</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.