11 days ago, Rachel had a total of 280 silver and white stickers. 30% of her stickers were white stickers. Today, her grandmother gave her some more stickers. As a result, her silver stickers increased by 25%. Now, 50% of her stickers are white stickers. How many white stickers did her grandmother give her?

	White stickers	Silver stickers	Total  stickers
Before	3 u	7 u	280
Change	+ 5.75 u	+ 1.75 u
After	8.75 u	8.75 u
Comparing the silver stickers and white stickers in the end	1	1

30% = ³⁰₁₀₀ = ³₁₀

White stickers : Silver stickers = 3 : 7

Increase in the number of silver stickers
= 25% x 7 u
= ²⁵₁₀₀ x 7 u
= 1.75 u

50% = ⁵⁰₁₀₀ = ¹₂

In the end
White stickers : Silver stickers = 1 : 1

Number of stickers at first
= 7 u + 3 u
= 10 u 

10 u = 280

1 u = 280 ÷ 10 = 28

Number of white stickers that Rachel received from her grandmother
= 8.75 u - 3 u
= 5.75 u
= 5.75 x 28
= 161

Answer(s): 161