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1. If 3a +5b = 10 and 5a + 3b = 30, what is the average (arithmetic mean) of a and b?
- A. 4
- B. 4
- C. 4
- D. 4
Answer: Option B
Explanation:
Hints: average = a + b /2
এখন, 3a + 5b + 5a + 3b = 10 + 30
8 (a + b) = 40
a + b = 40/8
a + b/2 = 40/8 × 2 = 40/16 = 2.5
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