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Solve for [tex]$x$[/tex] and [tex]$y$[/tex]:

[tex]\[
\begin{array}{l}
7y - 5x = 45 \\
x = 8 - 2y
\end{array}
\][/tex]

A. [tex]$x = 5, y = 10$[/tex]

B. [tex]$x = 4, y = 2$[/tex]


Sagot :

To solve for the values of [tex]\( x \)[/tex] and [tex]\( y \)[/tex] given the system of equations:
[tex]\[ \begin{aligned} 1. & \quad 7y - 5x = 45 \\ 2. & \quad x = 8 - 2y \end{aligned} \][/tex]

we will follow these steps:

1. Express [tex]\( y \)[/tex] in terms of [tex]\( x \)[/tex] from the second equation:

Start with the equation:
[tex]\[ x = 8 - 2y \][/tex]

Rearrange to solve for [tex]\( y \)[/tex]:
[tex]\[ 2y = 8 - x \\ y = \frac{8 - x}{2} \][/tex]

2. Substitute this expression for [tex]\( y \)[/tex] into the first equation:

Original first equation:
[tex]\[ 7y - 5x = 45 \][/tex]

Substitute [tex]\( y = \frac{8 - x}{2} \)[/tex]:
[tex]\[ 7 \left(\frac{8 - x}{2}\right) - 5x = 45 \][/tex]

3. Simplify and solve for [tex]\( x \)[/tex]:

Distribute and simplify:
[tex]\[ \frac{7(8 - x)}{2} - 5x = 45 \][/tex]
[tex]\[ \frac{56 - 7x}{2} - 5x = 45 \][/tex]

Multiply through by 2 to clear the fraction:
[tex]\[ 56 - 7x - 10x = 90 \][/tex]
[tex]\[ 56 - 17x = 90 \][/tex]

Subtract 56 from both sides:
[tex]\[ -17x = 34 \][/tex]

Divide by -17:
[tex]\[ x = \frac{34}{-17} \][/tex]
[tex]\[ x = -2 \][/tex]

4. Substitute [tex]\( x \)[/tex] back into the expression for [tex]\( y \)[/tex]:

Use the expression [tex]\( y = \frac{8 - x}{2} \)[/tex]:
[tex]\[ y = \frac{8 - (-2)}{2} \][/tex]
[tex]\[ y = \frac{8 + 2}{2} \][/tex]
[tex]\[ y = \frac{10}{2} \][/tex]
[tex]\[ y = 5 \][/tex]

Therefore, the solution to the given system of equations is:
[tex]\[ x = -2 \quad \text{and} \quad y = 5 \][/tex]

None of the given options ([tex]\( x = 5, y = 10 \)[/tex] or [tex]\( x = 4, y = 2 \)[/tex]) match this solution. So, neither option is correct.