How Many Mangoes?

mango puzzle
A girl was selling mangoes. To the first customer she sold half of her mangoes plus 1 mango free, and to the second customer she sold half of the remaining mangoes plus 2 mangoes free and to the third person she sold half of the remaining mangoes plus 3 mangoes free. This left her with two mangoes.

If so, how many mangoes did she start with?

Answer: