Question 393288
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In the first place, your system of equations is exactly correct presuming tha that the variable *[tex \Large s] represents the price of a senior citizen ticket and *[tex \Large c] represents the price of a child ticket.


You put this in the "Matrices/Determinant/Cramer's Rule" section, so I presume you want one of those methods.  Here's Cramer's Rule using determinants:


Find the determinant of the coefficient matrix:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ D\ =\ \left|a\ b\cr c\ d\right|\ =\ ad\ -\ cb]



*[tex \LARGE \ \ \ \ \ \ \ \ \ \ D\ =\ \left|\ \ 3\ \ 5\cr\ 12\ 12\right|\ =\ 36\ -\ 60]


Then substitute the constants into the first column and again calculate Determinant:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ D_s\ =\ \left|\ \ 70\ \ 5\cr\ 216\ 12\right|]


And substitute the constants into the second column and compute again.


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ D_c\ =\ \left|\ \ 3\ \ 70\cr\ 12\ 216\right|]


Finally, compute:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ s\ =\ \frac{D_s}{D}]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ c\ =\ \frac{D_c}{D}]


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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