There were some white pens and pink pens. The pens were packed into 2 bags. At first, Bag Q contained 220 pens and 30% of them were pink pens. Bag R contained 550 pens and 60% of them were pink pens. How many white pens and pink pens in total must be moved from Bag Q to Bag R such that 25% of the pens in Bag Q are white and 50% of the pens in Bag R are pink?

	Bag Q		Bag R
Total	220		550
	Pink pens	White pens	Pink pens	White pens
Before	66	154	330	220
Change	- ?	- ?	+ ?	+ ?
After	3 u	1 u	1 p	1 p

Number of pink pens in Bag Q at first
= 30% x 220
= ³⁰₁₀₀ x 220
= 66

Number of white pens in Bag Q at first
= 220 - 66
= 154

Number of pink pens in Bag R at first
= 60% x 550
= ⁶⁰₁₀₀ x 550
= 330

Number of white pens in Bag R at first
= 550 - 330
= 220

Bag Q in the end
25% = ²⁵₁₀₀ =¹₄
Pink pens : White pens = 3 : 1

Bag R in the end
50% = ⁵⁰₁₀₀ =¹₂
Pink pens : White pens = 1 : 1

Total number of pink pens = 3 u + 1 p

3 u + 1 p = 66 + 330
3 u + 1 p = 396 

1 p = 396 - 3 u --- (1)

Total number of white pens = 1 u + 1 p
1 u + 1 p = 154 + 220
1 u + 1 p = 374

1 p = 374 - 1 u --- (2)

(2) = (1)
374 - 1 u = 396 - 3 u
3 u - 1 u = 396 - 374
2 u = 22

1 u = 22 ÷ 2 = 11

Total number of white pens and pink pens that must be moved from Bag Q to Bag R
= 220 - 4 u
= 220 - 4 x 11
= 220 - 44
= 176

Answer(s): 176