Question 1196230
.
During one month, a homeowner used 200 units of electricity and 110 units of gas for a total cost of $87.80. 
The next month, 240 units of electricity and 200 units of gas were used for a total cost of $117.60. 
Find the cost per unit of gas.
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<pre>
Write the system of two equations

    200e + 110g = 87.80

    240e + 200g = 117.60


where "e" is the price for the unit of electricity and "g" is the price for the unit of gas.


Solve using determinants


    g = {{{(200*117.60 - 240*87.80)/(200*200 - 240*110)}}} = 0.18.


<U>ANSWER</U>. The cost per unit of gas is 0.18.
</pre>

Solved.


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On the &nbsp;Determinants' method for solving systems of two linear equations in two unknowns see the lesson 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF =http://www.algebra.com/algebra/homework/coordinate/lessons/Solution-of-the-lin-syst-of-two-eqns-with-two-unknowns-using-det.lesson>Solution of the linear system of two equations in two unknowns using determinant</A> 

in this site.


Also, &nbsp;you have this free of charge online textbook in &nbsp;ALGEBRA-I &nbsp;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 lesson is the part of this online textbook under the topic &nbsp;"<U>Systems of two linear equations in two unknowns</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.