Hazel had some chocolate bars. She sold 20% of her chocolate bars and gave half of the remainder to her cousin. After that, she bought 30 chocolate bars and had a total of 42 chocolate bars in the end. How many chocolate bars did Hazel have at first?
Percentage of chocolate bars that Hazel left after selling 205 of her chocolate bars
= 100% - 20%
= 80%

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

Number of chocolate bars that Hazel had left = 2 u

Number of chocolate bars that Hazel had in the end = 2 u + 30

2 u + 30 = 42
2 u = 42 - 30
2 u = 12

1 u = 12 ÷ 2 = 6

Total number of chocolate bars that Hazel had at first
= 5 u
= 5 x 6
= 30

Answer(s): 30