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Mohan gets 3 marks for each correct sum and loses 2 marks for each wrong sum. He attempts 30 sums and obtains 40 marks. The number of sums solved correctly is :
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- 15
- 20
- 25
- 10
Correct Option: B
If the number of correct sums be x, then,
x × 3 – (30 –x) × 2 = 40
⇒ 3x – 60 + 2x = 40
⇒ 5x = 60 + 40 = 100
⇒ x = 20
