Dad bought some chocolates and shared them with his sister. My sister ate five, and my sister ate four, which was exactly half. Dad bought it back?

My sister ate 5 pieces, accounting for half of her total, so my sister had 5×2= 10 pieces.

My sister ate 4 pieces, which is half of her total, so my sister has 4×2=8 pieces.

10+8= 18

* * * Yes 18 chocolate.