Math worksheet with addition problems and a riddle involving a talking dog.

Problem Overview:

The task involves solving a series of 3-digit addition problems and then using the results to solve a riddle. The additions are grouped into pairs, and each pair corresponds to a letter. After solving the additions, we match the sums to the letters in the riddle to reveal the answer.

Step-by-Step Solution:

#### 1. Solve the Addition Problems:

We will solve each addition problem step by step.

##### Pair P (745 + 539):
\[
\begin{array}{r}
745 \\
+ 539 \\
\hline
1284 \\
\end{array}
\]
- Sum: 1284

##### Pair A (429 + 773):
\[
\begin{array}{r}
429 \\
+ 773 \\
\hline
1202 \\
\end{array}
\]
- Sum: 1202

##### Pair G (639 + 880):
\[
\begin{array}{r}
639 \\
+ 880 \\
\hline
1519 \\
\end{array}
\]
- Sum: 1519

##### Pair B (899 + 243):
\[
\begin{array}{r}
899 \\
+ 243 \\
\hline
1142 \\
\end{array}
\]
- Sum: 1142

##### Pair E (753 + 287):
\[
\begin{array}{r}
753 \\
+ 287 \\
\hline
1040 \\
\end{array}
\]
- Sum: 1040

##### Pair I (523 + 445):
\[
\begin{array}{r}
523 \\
+ 445 \\
\hline
968 \\
\end{array}
\]
- Sum: 968

##### Pair S (432 + 98):
\[
\begin{array}{r}
432 \\
+ 98 \\
\hline
530 \\
\end{array}
\]
- Sum: 530

##### Pair N (326 + 876):
\[
\begin{array}{r}
326 \\
+ 876 \\
\hline
1202 \\
\end{array}
\]
- Sum: 1202

##### Pair L (456 + 22):
\[
\begin{array}{r}
456 \\
+ 22 \\
\hline
478 \\
\end{array}
\]
- Sum: 478

##### Pair E (326 + 427):
\[
\begin{array}{r}
326 \\
+ 427 \\
\hline
753 \\
\end{array}
\]
- Sum: 753

##### Pair L (428 + 98):
\[
\begin{array}{r}
428 \\
+ 98 \\
\hline
526 \\
\end{array}
\]
- Sum: 526

##### Pair E (331 + 531):
\[
\begin{array}{r}
331 \\
+ 531 \\
\hline
862 \\
\end{array}
\]
- Sum: 862

#### 2. Match the Sums to the Letters:

Now, we match the sums to the corresponding letters:

- P: 1284
- A: 1202
- G: 1519
- B: 1142
- E: 1040
- I: 968
- S: 530
- N: 1202
- L: 478
- E: 753
- L: 526
- E: 862

#### 3. Solve the Riddle:

The riddle is: "What is even more amazing than a talking dog?"

The sums correspond to the following letters:
- 1284 → P
- 1202 → A
- 1519 → G
- 1142 → B
- 1040 → E
- 968 → I
- 530 → S
- 1202 → N
- 478 → L
- 753 → E
- 526 → L
- 862 → E

Using these letters, we form the word: "PAGELINESELLE".

However, upon closer inspection, the intended answer seems to be a simpler phrase. Let's re-evaluate the matching:

- The unique sums and their corresponding letters should spell out the answer.
- The correct matching appears to be:
- 1284 → P
- 1202 → A
- 1519 → G
- 1142 → B
- 1040 → E
- 968 → I
- 530 → S
- 1202 → N
- 478 → L
- 753 → E
- 526 → L
- 862 → E

Reorganizing these letters, the answer is: "PAGE LINE SELLE", which simplifies to "PAGE LINE SELLE" or "PAGE LINE SELLE".

Final Answer:

\[
\boxed{\text{A TALKING DOG WITH A PAGE-LINE SELLE}}
\]