Solve the system of equations using substitution and identify the solution. List your answers alphabetically in the ordered pairs.

[tex]\[
\begin{array}{l}
2c - d = -2 \\
4c + d = 20
\end{array}
\][/tex]

A. [tex]\((20, 9)\)[/tex]
B. [tex]\((3, 8)\)[/tex]
C. [tex]\((9, 20)\)[/tex]
D. [tex]\((8, 3)\)[/tex]
E. No Solution
F. Infinitely Many Solutions



Answer :

To solve the system of equations using substitution, follow these steps:

1. Write down the equations:
[tex]\[ \begin{array}{l} 2c - d = -2 \quad \text{(Equation 1)} \\ 4c + d = 20 \quad \text{(Equation 2)} \end{array} \][/tex]

2. Solve Equation 1 for [tex]\( d \)[/tex]:
[tex]\[ 2c - d = -2 \implies d = 2c + 2 \][/tex]

3. Substitute [tex]\( d = 2c + 2 \)[/tex] into Equation 2:
[tex]\[ 4c + (2c + 2) = 20 \][/tex]

4. Combine like terms:
[tex]\[ 4c + 2c + 2 = 20 \implies 6c + 2 = 20 \][/tex]

5. Solve for [tex]\( c \)[/tex]:
[tex]\[ 6c + 2 = 20 \implies 6c = 18 \implies c = 3 \][/tex]

6. Substitute [tex]\( c = 3 \)[/tex] back into the expression for [tex]\( d \)[/tex]:
[tex]\[ d = 2c + 2 \implies d = 2(3) + 2 \implies d = 6 + 2 \implies d = 8 \][/tex]

7. Write the solution as an ordered pair:
[tex]\[ (c, d) = (3, 8) \][/tex]

8. Verify the solution:
Substitute [tex]\( c = 3 \)[/tex] and [tex]\( d = 8 \)[/tex] back into the original equations to ensure both are satisfied:
- For Equation 1: [tex]\( 2(3) - 8 = 6 - 8 = -2 \)[/tex] (True)
- For Equation 2: [tex]\( 4(3) + 8 = 12 + 8 = 20 \)[/tex] (True)

Since both equations are satisfied, the solution to the system of equations is [tex]\( (3, 8) \)[/tex].

Therefore, the correct answer is:
[tex]\[ (3, 8) \][/tex]