# Two naughty boys...

Level pending

Brenda has an infinite number of coins. Unfortunately, her 2 mischievous younger brothers, Brian and Billy, stole an increasing number of coins from her. The first day, Brian stole 1 coin from her, the second day, 2 , the third day, 3 and so on. Billy stole 1 coin on the second day, 2 coins on the fourth day, 3 coins on the sixth day and so on. Up to the nth day, Brenda lost $$\frac{an^2 + bn}{c}$$ coins (this expression is in its simplest form). a+b+c= ?

Assumptions: n is an even number.

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