All questions of We Distribute, Yet Things Multiply for Class 8 Exam

Given Values
- a = 10
- b = 6
Expression to Evaluate
We need to evaluate the expression:
7(a + b) - 3(a - b)
Step 1: Calculate a + b
- a + b = 10 + 6 = 16
Step 2: Calculate a - b
- a - b = 10 - 6 = 4
Step 3: Substitute into the Expression
Now substitute the values into the expression:
7(a + b) - 3(a - b)
= 7(16) - 3(4)
Step 4: Perform the Multiplications
- 7(16) = 112
- 3(4) = 12
Step 5: Final Calculation
Now, we perform the final calculation:
112 - 12 = 100
Conclusion
The evaluated expression is 100. Since the problem states the correct answer is option 'A', it seems there may be a misunderstanding regarding the options provided. Based on our calculation, the correct value is 100.

Understanding the Expression
To simplify the expression 8 × (25 + 15), we need to follow the order of operations.
Step 1: Solve Inside the Parentheses
- First, calculate the sum inside the parentheses:
- 25 + 15 = 40
Step 2: Multiply by 8
- Now, substitute back into the expression:
- 8 × 40
Step 3: Perform the Multiplication
- Next, carry out the multiplication:
- 8 × 40 = 320
Final Result
- The simplified expression is 320.
Conclusion
Thus, the correct answer is option 'B' which is 320.
This step-by-step approach helps in understanding how to simplify the expression accurately.

Understanding the Problem
To simplify the expression (12 + 18) × 7, we will use the distributive property. The distributive property states that a(b + c) = ab + ac. In this case, we can first simplify the addition inside the parentheses.
Step 1: Simplify the Addition
- Calculate 12 + 18:
- 12 + 18 = 30
So, we can rewrite the expression as:
- (12 + 18) × 7 = 30 × 7
Step 2: Multiply
Now we need to multiply 30 by 7:
- 30 × 7 = 210
Final Result
Thus, the simplified expression is 210. Since the question states options, we can conclude:
- The correct answer is option 'A': 210
Why the Other Options are Incorrect
- Option B (2100): This is incorrect because it is 10 times larger than the actual result.
- Option C (252): This does not relate to any calculation in the expression.
- Option D (420): This is double the correct answer, likely due to a multiplication error.
Conclusion
Using the distributive property to simplify the expression (12 + 18) × 7 leads us to the correct answer of 210, confirming that option 'A' is accurate. Understanding each step helps in mastering such problems!