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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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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 = = 0.18 dollars. ANSWER
Solved.
Do not be scared seeing this long formula filled with numbers.
You can get the answer in ONE CLICK copying this formula into the Excel spreadsheet
or using this convenient online calculator www.desmos.com
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On the Determinants' method for solving systems of two linear equations in two unknowns see the lesson
- Solution of the linear system of two equations in two unknowns using determinant
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lesson is the part of this online textbook under the topic "Systems of two linear equations in two unknowns".
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.