Select the correct answer.

Create and solve a linear equation that represents the model, where circles and a square are shown evenly balanced on a balance beam.

A. [tex]x + 7 = 12; \, x = 5[/tex]
B. [tex]x + 5 = 7; \, x = 2[/tex]
C. [tex]x = 5 + 7; \, x = 12[/tex]
D. [tex]x + 7 = 5; \, x = -2[/tex]



Answer :

We need to determine which of the provided equations is correctly solved for [tex]\( x \)[/tex]. Let's analyze each option step-by-step.

### Option 1: [tex]\( x + 7 = 12 \)[/tex]
1. To isolate [tex]\( x \)[/tex], subtract 7 from both sides:
[tex]\[ x + 7 - 7 = 12 - 7 \][/tex]
2. Simplify to get:
[tex]\[ x = 5 \][/tex]
3. Check by substituting [tex]\( x = 5 \)[/tex] into the equation:
[tex]\[ 5 + 7 = 12 \][/tex]
[tex]\[ 12 = 12 \][/tex]
4. This is a valid solution.

### Option 2: [tex]\( x + 5 = 7 \)[/tex]
1. To isolate [tex]\( x \)[/tex], subtract 5 from both sides:
[tex]\[ x + 5 - 5 = 7 - 5 \][/tex]
2. Simplify to get:
[tex]\[ x = 2 \][/tex]
3. Check by substituting [tex]\( x = 2 \)[/tex] into the equation:
[tex]\[ 2 + 5 = 7 \][/tex]
[tex]\[ 7 = 7 \][/tex]
4. This is a valid solution.

### Option 3: [tex]\( x = 5 + 7 \)[/tex]
1. Simplify the right-hand side:
[tex]\[ x = 12 \][/tex]
2. This equation does not need further verification since it directly provides the value of [tex]\( x \)[/tex]. However, note that this equation does not represent the format typical for solving standard linear equations of the form "ax + b = c" used in the problem context.

### Option 4: [tex]\( x + 7 = 5 \)[/tex]
1. To isolate [tex]\( x \)[/tex], subtract 7 from both sides:
[tex]\[ x + 7 - 7 = 5 - 7 \][/tex]
2. Simplify to get:
[tex]\[ x = -2 \][/tex]
3. Check by substituting [tex]\( x = -2 \)[/tex] into the equation:
[tex]\[ -2 + 7 = 5 \][/tex]
[tex]\[ 5 = 5 \][/tex]
4. This is a valid solution.

Given the options and their validations, Options 1, 2, and 4 correctly solve their respective linear equations. However, if we consider valid linear equation formats typically used in such questions, we prefer those that strictly follow the linear form [tex]\( x + a = b \)[/tex].

Therefore, the best choice considering all aspects is:
[tex]\[ x + 7 = 12 ; x = 5 \][/tex]
Hence, the correct answer is:
[tex]\[ \boxed{1} \][/tex]