Apply addition and subtraction rules

Key notes:

➕ Addition of Integers

Same sign → Add the numbers, keep the same sign.

• Example: +5 + +3 = +8 😊
• Example: –7 + –2 = –9 😐

Different signs → Subtract the smaller number from the bigger number, keep the sign of the bigger number (in value).

• Example: –8 + +3 = –5
• Example: +10 + –6 = +4

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➖ Subtraction of Integers

Use the rule:

💡 Subtracting a number = Adding its opposite

• Example: 7 – 4 = 7 + (–4) = 3
• Example: –6 – 3 = –6 + (–3) = –9
• Example: –2 – (–5) = –2 + +5 = +3 🎉

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🔢 Order Matters in Subtraction

Subtraction is not commutative (changing the order changes the answer).

• Example: 7 – 3 = 4
• Example: 3 – 7 = –4

Addition is commutative.

• Example: 4 + 6 = 6 + 4 ✔️

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🎈 Apply Rules in Expressions

When solving expressions like:

• +12 – 7 + (–5)
  • Convert subtraction → addition
  • 12 + (–7) + (–5) = 12 – 7 – 5 = 0

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🧮 Use Number Line (Visual)

Moving right ➡️ = adding

Moving left ⬅️ = subtracting

Helps understand positive and negative movement.

• Example: Start at –3, move +5 steps → end at +2 🎯

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🎯 Combine Like Terms

When variables are involved:

Only combine terms with the same variable and exponent

Example:

• 3a + 5a = 8a
• 7x – 2x = 5x
• 4y – (–3y) = 4y + 3y = 7y

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✨ Check Using Opposites

A number and its opposite always add to zero

• Example: +7 + –7 = 0

Helps verify your answers quickly! ✔️

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🧠 Real-Life Application

Use addition and subtraction rules with:

• Profit & loss 💵
• Temperature rise & fall 🌡️
• Elevation above and below sea level ⛰️
• Bank deposits and withdrawals 🏦

Learn with an example