Select the best answer for the question.

Solve the system of equations [tex]2x + 3y = 40[/tex] and [tex]-2x + 2y = 20[/tex].

A. [tex]x = -6, y = 4[/tex]
B. [tex]x = -10, y = 20[/tex]
C. [tex]x = 2, y = 12[/tex]
D. [tex]x = 10, y = 20[/tex]



Answer :

To solve the system of equations [tex]\(2x + 3y = 40\)[/tex] and [tex]\(-2x + 2y = 20\)[/tex], we'll use the substitution or elimination method. Here's the step-by-step process:

1. Write down the given equations:
[tex]\[ 2x + 3y = 40 \quad \text{(Equation 1)} \][/tex]
[tex]\[ -2x + 2y = 20 \quad \text{(Equation 2)} \][/tex]

2. Add the two equations together to eliminate [tex]\(x\)[/tex]:
[tex]\[ (2x + 3y) + (-2x + 2y) = 40 + 20 \][/tex]
Simplifying this, we get:
[tex]\[ 2x - 2x + 3y + 2y = 60 \][/tex]
[tex]\[ 0x + 5y = 60 \][/tex]
[tex]\[ 5y = 60 \][/tex]

3. Solve for [tex]\(y\)[/tex]:
[tex]\[ y = \frac{60}{5} \][/tex]
[tex]\[ y = 12 \][/tex]

4. Substitute [tex]\(y = 12\)[/tex] back into one of the original equations to solve for [tex]\(x\)[/tex]:
Using Equation 1:
[tex]\[ 2x + 3(12) = 40 \][/tex]
[tex]\[ 2x + 36 = 40 \][/tex]
[tex]\[ 2x = 40 - 36 \][/tex]
[tex]\[ 2x = 4 \][/tex]
[tex]\[ x = \frac{4}{2} \][/tex]
[tex]\[ x = 2 \][/tex]

5. Verifying the solution with the second equation:
Substituting [tex]\(x = 2\)[/tex] and [tex]\(y = 12\)[/tex] into Equation 2:
[tex]\[ -2(2) + 2(12) = 20 \][/tex]
[tex]\[ -4 + 24 = 20 \][/tex]
[tex]\[ 20 = 20 \quad \text{(True)} \][/tex]

Therefore, the solution to the system of equations is [tex]\(x = 2\)[/tex] and [tex]\(y = 12\)[/tex].

The best answer is:
C. [tex]\(x=2, y=12\)[/tex]