Sabrina had some chocolate bars. She sold 70% of her chocolate bars and gave half of the remainder to her brother. After that, she bought 36 chocolate bars and had a total of 57 chocolate bars in the end. How many chocolate bars did Sabrina have at first?
Percentage of chocolate bars that Sabrina left after selling 705 of her chocolate bars
= 100% - 70%
= 30%

Fraction of chocolate bars that Sabrina had left after giving to her brother
= ¹₂ x 30%
= ³₂₀

Number of chocolate bars that Sabrina had left = 3 u

Number of chocolate bars that Sabrina had in the end = 3 u + 36

3 u + 36 = 57
3 u = 57 - 36
3 u = 21

1 u = 21 ÷ 3 = 7

Total number of chocolate bars that Sabrina had at first
= 20 u
= 20 x 7
= 140

Answer(s): 140