Question 200236
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Let *[tex \Large x] represent the number of minutes you use.  Then, if you convert $5.00 to 500 cents, the total cost of the first plan is:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 500 + 2x]


The total cost of the second plan is:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 4(100 + x)]


You are interested in the value of x when the two costs are equal, so set the two expressions equal to each other and solve for *[tex \Large x]:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 4(100 + x) = 500 + 2x]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 400 + 4x = 500 + 2x]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 4x - 2x = 500 - 400]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2x = 100]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ x = 50]


Check:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 500 + 2(50) = 600]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 4(100 + 50) = 4(150) = 600]


They are the same, so the answer checks.



John
*[tex \LARGE e^{i\pi} + 1 = 0]
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