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Use the substitution method to solve the system of equations. Choose the correct ordered pair.

[tex]\[
\begin{array}{l}
y = 7x + 8 \\
y = x + 20
\end{array}
\][/tex]

A. [tex]\((2, 22)\)[/tex]

B. [tex]\((3, 29)\)[/tex]

C. [tex]\((2, 8)\)[/tex]

D. [tex]\((7, 8)\)[/tex]


Sagot :

Sure, let's solve the system of equations using the substitution method.

Given the equations:
[tex]\[ \begin{array}{l} y = 7x + 8 \quad \text{(Equation 1)} \\ y = x + 20 \quad \text{(Equation 2)} \end{array} \][/tex]

To solve this system, we will set the right sides of the equations equal to each other since both equations are equal to [tex]\( y \)[/tex].

So,
[tex]\[ 7x + 8 = x + 20 \][/tex]

Next, we need to isolate [tex]\( x \)[/tex] by first eliminating [tex]\( x \)[/tex] from one side of the equation:

[tex]\[ 7x + 8 - x = x + 20 - x \][/tex]

This simplifies to:
[tex]\[ 6x + 8 = 20 \][/tex]

Now, subtract 8 from both sides to further isolate [tex]\( x \)[/tex]:

[tex]\[ 6x + 8 - 8 = 20 - 8 \][/tex]

This simplifies to:
[tex]\[ 6x = 12 \][/tex]

Next, divide both sides by 6:

[tex]\[ x = \frac{12}{6} \][/tex]

So,
[tex]\[ x = 2 \][/tex]

With [tex]\( x \)[/tex] found, substitute [tex]\( x = 2 \)[/tex] back into one of the original equations to solve for [tex]\( y \)[/tex]. Using Equation 1:
[tex]\[ y = 7x + 8 \][/tex]

Substitute [tex]\( x = 2 \)[/tex]:
[tex]\[ y = 7(2) + 8 \][/tex]

This simplifies to:
[tex]\[ y = 14 + 8 \][/tex]

So,
[tex]\[ y = 22 \][/tex]

The ordered pair that solves this system of equations is:
[tex]\[ (x, y) = (2, 22) \][/tex]

Thus, the correct choice is:
A. [tex]\((2, 22)\)[/tex]