Risa has 30% as many pens as Roshel. Roshel has 110% as many pens as Shiyun. If Roshel gives 50 pens to Shiyun, both will then have an equal number of pens. Find the average number of pens the three of them have.

Risa	Roshel	Shiyun
3x11	10x11
	11x10	10x10
33 u	110 u	100 u

30% = ³⁰₁₀₀ = ³₁₀
110% = ¹¹⁰₁₀₀= ¹¹₁₀

The number of pens that Risa has is repeated.  Make the number of pens that Risa has the same. LCM of 10 and 11 is 110.

	Roshel	Shiyun	Total
Before	110 u	100 u	210 u
Change	- 5 u	+ 5 u
After	105 u	105 u	210 u

Total number of pens that Roshel and Shiyun have
= 110 u + 100 u
= 210 u

After Roshel gives to Shiyun, both of them will have the same number of pens. 

The total number of pens that Roshel and Shiyun have remains unchanged.

Number of pens that each of them will have
= 210 u ÷ 2
= 105 u

Number of pens that Roshel gives to Shiyun
= 110 u - 105 u
= 5 u

5 u = 50

1 u = 50 ÷ 5 = 10

Total number of pens that three of them have
= 210 u + 33 u
= 243 u

Average number of pens that each of them have
= 243 u ÷ 3
= 81 u
= 81 x 10
= 810

Answer(s): 810