Question 234601
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Let *[tex \Large x] represent the number of hours that Amy worked.  Since they worked a total of 30 hours, Kim must have then worked *[tex \Large 30\ -\ x] hours.  Amy was paid *[tex \Large 8x] dollars for her work, and Kim was paid *[tex \Large 12(30\ -\ x)] for her work.  Together they earned $308, so:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 8x\ +\ 12(30\ -\ x)\ =\ 308]


You could also have just said *[tex \Large x] is Amy's hours, and *[tex \Large y] is Kim's hours and then made a system of two 2-variable equations:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ x\ +\ y\ =\ 30]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 8x\ +\ 12y\ =\ 308]


But once you start to solve it by substitution, you would end up with either


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 8x\ +\ 12(30\ -\ x)\ =\ 308]


or


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 8(30\ -\ y)\ +\ 12y\ =\ 308]


anyway.


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