Mr Huang collected 240 more local stamps than foreign stamps in January. In February, the number of local stamps collected was 20% more while the number of foreign was 30% fewer than in January. In February, Mr Huang collected a total of 497 stamps. If Mr Huang bought each local stamp at $0.60 and each foreign stamp at $1.10, how much change did he receive if he gave the cashier a $1000 note for his February collection?

Let's denote:

- The number of local stamps Mr. Huang collected in January as $ L $.
- The number of foreign stamps Mr. Huang collected in January as $ F $.

According to the problem, we know that:

1. $ L = F + 240 $ (Mr. Huang collected 240 more local stamps than foreign stamps in January).
2. In February, the number of local stamps collected was 20% more than in January, so the number of local stamps in February is $ 1.2L $.
3. In February, the number of foreign stamps collected was 30% fewer than in January, so the number of foreign stamps in February is $ 0.7F $.
4. In February, Mr. Huang collected a total of 497 stamps, so:
   \[
   1.2L + 0.7F = 497
   \]

Now, let's solve this system of equations step by step.

### Step 1: Substituting $ L = F + 240 $ into the February total equation
Substitute $ L $ in terms of $ F $ into the February total equation:
\[
1.2(F + 240) + 0.7F = 497
\]
Expand and simplify:
\[
1.2F + 288 + 0.7F = 497
\]
\[
1.9F + 288 = 497
\]
\[
1.9F = 497 - 288
\]
\[
1.9F = 209
\]
\[
F = \frac{209}{1.9} = 110
\]

### Step 2: Calculate $ L $
Now, using $ L = F + 240 $:
\[
L = 110 + 240 = 350
\]

### Step 3: Calculate the number of stamps in February
- The number of local stamps in February is:
  \[
  1.2L = 1.2 \times 350 = 420
  \]
- The number of foreign stamps in February is:
  \[
  0.7F = 0.7 \times 110 = 77
  \]

### Step 4: Total cost of stamps in February
- The cost of local stamps is:
  \[
  420 \times 0.60 = 252
  \]
- The cost of foreign stamps is:
  \[
  77 \times 1.10 = 84.7
  \]

Thus, the total cost of the stamps in February is:
\[
252 + 84.7 = 336.7
\]

### Step 5: Calculate the change received
If Mr. Huang gave the cashier a $1000 note, the change he received is:
\[
1000 - 336.7 = 663.3
\]

### Final Answer:
Mr. Huang received **$663.30** in change.

Would you like more details or have any questions?

Here are some related questions to explore:
1. How many total stamps did Mr. Huang collect in January?
2. How much did Mr. Huang spend in January if the prices were the same?
3. What is the percentage of local stamps out of the total in February?
4. If the price of foreign stamps increased by 10%, how much more would Mr. Huang have paid?
5. How many foreign stamps did Mr. Huang collect in both months combined?

**Tip:** When solving percentage-based problems, always express percentage increases or decreases as decimal multipliers (e.g., 20% more is 1.2).

This problem explores how Mr. Huang's stamp collection changes between two months, using percentage increase and decrease. Learn how to solve the system of equations step-by-step and calculate the total cost of stamps and the change received when a $1000 note is given. Suitable for Grades 8-10 students.

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