Question 1179778
.
During one month, a homeowner used 300 units of electricity and 140 units of gas 
for a total cost of $106.20. The next month, 250 units of electricity and 250 units of gas
 were used for a total cost of $112.50. Find the cost per unit of gas.
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<pre>
Write equations as you read 


    300E + 140G = 106.20     (1)

    250E + 250G = 112.50     (2)



You need find G.  Use the determinant method (the Cramer's rule)



    G = {{{(300*112.50 - 250*106.20)/(300*250-250*140)}}} = 0.18  dollars.    <U>ANSWER</U>
</pre>

Solved.


Do not be scared seeing this long formula filled with numbers.

You can get the answer in &nbsp;ONE &nbsp;CLICK &nbsp;copying this formula into the &nbsp;Excel spreadsheet 
or using this convenient online calculator www.desmos.com


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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.