College

Marley solved \(345 - 176\) and then checked her work. Which pair of number sentences did she use?

A. \[ 345 - 176 = 169 \]
\[ 176 - 169 = 7 \]

B. \[ 345 - 176 = 169 \]
\[ 345 + 176 = 521 \]

C. \[ 345 - 176 = 169 \]
\[ 345 - 169 = 176 \]

D. \[ 345 - 176 = 169 \]

Answer :

To solve the problem where Marley checked her subtraction, we need to determine which pair of number sentences confirms that her solution is correct.

First, let's look at Marley's subtraction:
[tex]\[ 345 - 176 = 169 \][/tex]

Now we need to check which pair of number sentences correctly verifies this solution. We'll do this by examining each pair of sentences given in the options:

### Option A:
1. [tex]\( 345 - 176 = 169 \)[/tex]
2. [tex]\( 176 - 169 = 7 \)[/tex]

Checking the first statement: [tex]\( 345 - 176 = 169 \)[/tex]. This is correct based on Marley's solution.
Checking the second statement: [tex]\( 176 - 169 = 7 \)[/tex]. This is not correct because:
[tex]\[ 176 - 169 = 7 \quad \text{(which is true)} \][/tex]
This pair, therefore, has inconsistent logic for verification.

### Option B:
1. [tex]\( 345 - 176 = 169 \)[/tex]
2. [tex]\( 345 + 176 = 521 \)[/tex]

Checking the first statement: [tex]\( 345 - 176 = 169 \)[/tex]. This is correct.
Checking the second statement: [tex]\( 345 + 176 = 521 \)[/tex]. This does not relate logically to verifying the initial subtraction.

### Option C:
1. [tex]\( 345 - 176 = 169 \)[/tex]
2. [tex]\( 345 - 169 = 176 \)[/tex]

Checking the first statement: [tex]\( 345 - 176 = 169 \)[/tex]. This is correct.
Checking the second statement: [tex]\( 345 - 169 = 176 \)[/tex]. Here we verify the original subtraction because if:
[tex]\[ 345 - 169 = 176 \quad \text{(which is true)} \][/tex]
This shows that changing the order of subtraction still holds true.

### Option D:
1. [tex]\( 345 - 176 = 169 \)[/tex]

This option does not provide a complementary step to verify the correctness.

Given the analysis, the only option that provides correct and logical verification for Marley's solution is:
[tex]\[ \boxed{C} \][/tex]