You and your friend are selling tickets to a charity event. you sell 9 adult tickets and 13 student tickets for 212$. your friend sells 4 adult tickets and 15 student tickets for $168.what is the cost of student ticket?

  $8

Step-by-step explanation:

Let a and s represent the prices of adult and student tickets, respectively. The relations described by the problem statement can be written ...

  9a +13s = 212

  4a +15s = 168

Using Cramer's method, we can find the value of s to be ...

  s = (212·4 -168·9)/(13·4 -15·9) = -664/-83 = 8

The price of a student ticket is $8.

Comment on Cramer's method

For the equations ...

the solutions can be written as ...

This method is useful when the equation's coefficients don't lend themselves to "nice" arithmetic or when the value of only one variable is needed (as here).

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If you look up "Cramer's Method" in Wikipedia or other sources, you will likely find that the signs of the differences are reversed. That is, ...

  x = (ce-bf)/(ae-bd)

This makes no difference to the result of the calculation. The variable ordering shown here can be remembered as a pattern of Xs when compared to the locations of the coefficients in the given equations. Often, this permits the problem to be completely solved mentally.

the answer is b. 60. each interior angle in 120, so the exterior angle must be 60 in order to add up to 180

step-by-step explanation: