Question 1172204
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<pre>

Let x be the amount of the material worth $0.15 per kilogram. (I even do not want to use its long name)


Then the amount of the other material is (300-x) kilograms.


Now you write the total money equation


    0.15x + 0.1*(300-x) = 0.13*300.


Left side is the total cost of ingredients, while the right side is the cost of the final mixture.


From the equation, you get


    x = {{{(0.13*300-0.1*300)/(0.15-0.1)}}} = 180.


<U>ANSWER</U>.  180 kg of the decorative garden mixture and the rest material, 300-180 = 120 kg is the common stone.
</pre>

Solved.


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It is a standard and typical mixture problem.


In this site, there is entire bunch of lessons covering various types of mixture problems


&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=http://www.algebra.com/algebra/homework/word/mixtures/Solving-typical-word-problems-on-mixtures-for-dry-substances-coffee-nuts.lesson>Word problems on mixtures for dry substances like coffee beans, nuts, cashew and peanuts</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-dry-substances-like-cookies-candies.lesson>Word problems on mixtures for dry substances like candies, dried fruits</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-dry-substances-like-soil-and-sand.lesson>Word problems on mixtures for dry substances like soil and sand</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=http://www.algebra.com/algebra/homework/word/mixtures/OVERVIEW-of-lesson-on-word-problems-for-mixtures.lesson>OVERVIEW of lessons on word problems for mixtures</A>



A convenient place to quickly observe these lessons from a &nbsp;"bird flight height" &nbsp;(a top view) &nbsp;is the last lesson in the list.


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


Also, 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.



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I want to add my thoughts about the @josgarithmetic solution.



When a visitor comes to this forum with such problem, &nbsp;it is naturally to assume that this person is a beginner 
and does not know how to solve it.


Typically, &nbsp;it is a young student of &nbsp;6th -7th &nbsp;grade.


Such students practically &nbsp;NEVER &nbsp;worked with symbolic equations; and, &nbsp;typically, &nbsp;they &nbsp;DO &nbsp;NOT &nbsp;UNDERSTAND &nbsp;them, &nbsp;at all.


In middle school, &nbsp;the teachers &nbsp;NEVER &nbsp;teach students solving such problems using symbolic equations.



THEREFORE, &nbsp;I insistently recommend all visitors to ignore this and similar posts by @josgarithmetic.