Zack bought a coat for $69.78. He paid with $100 bill and received $26.73 in change. How much was the sales tax?
2 answers:
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The value of x satisfies both -9x + 4y = 8 and -3x - y = 4 given the same value of y is
Step-by-step explanation:
The system of equations has two equations:
- -9x + 4y = 8
- -3x - y = 4
Let us solve the system of equations to find the value of x and substitute it in the two equations to check if it gives the same value of y in the two equations
∵ -9x + 4y = 8 ⇒ (1)
∵ -3x - y = 4 ⇒ (2)
- Multiply equation (2) by 4 to make the coefficients of y in the
two equations have same value and different signs
∴ -12x - 4y = 16 ⇒ (3)
- Add equations (1) and (3) to eliminate y
∴ -21x = 24
- Divide both sides by -21
∴ x =
Let us substitute this value of x in equations (1) and (2) to find y
∵ -9( ) + 4y = 8
∴ + 4y = 8
- Subtract from both sides
∴ 4y =
- Divide both sides by 4
∴ y =
∵ -3( ) - y = 4
∴ - y = 4
- Subtract from both sides
∴ - y =
- Divide both sides by -1
∴ y =
The value of x satisfies both -9x + 4y = 8 and -3x - y = 4 given the same value of y is
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You can learn more about the system of equations in brainly.com/question/2115716
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