Tammy had some chocolate bars. She sold 20% of her chocolate bars and gave half of the remainder to her brother. After that, she bought 40 chocolate bars and had a total of 54 chocolate bars in the end. How many chocolate bars did Tammy have at first?
Percentage of chocolate bars that Tammy left after selling 205 of her chocolate bars
= 100% - 20%
= 80%

Fraction of chocolate bars that Tammy had left after giving to her brother
= ¹₂ x 80%
= ²₅

Number of chocolate bars that Tammy had left = 2 u

Number of chocolate bars that Tammy had in the end = 2 u + 40

2 u + 40 = 54
2 u = 54 - 40
2 u = 14

1 u = 14 ÷ 2 = 7

Total number of chocolate bars that Tammy had at first
= 5 u
= 5 x 7
= 35

Answer(s): 35