Cathy has 25% as many pens as Zara. Zara has 130% as many pens as Barbara. If Zara gives 24 pens to Barbara, both will then have an equal number of pens. Find the average number of pens the three of them have.

Cathy	Zara	Barbara
1x13	4x13
	13x4	10x4
13 u	52 u	40 u

25% = ²⁵₁₀₀ = ¹₄
130% = ¹³⁰₁₀₀= ¹³₁₀

The number of pens that Cathy has is repeated.  Make the number of pens that Cathy has the same. LCM of 4 and 13 is 52.

	Zara	Barbara	Total
Before	52 u	40 u	92 u
Change	- 6 u	+ 6 u
After	46 u	46 u	92 u

Total number of pens that Zara and Barbara have
= 52 u + 40 u
= 92 u

After Zara gives to Barbara, both of them will have the same number of pens. 

The total number of pens that Zara and Barbara have remains unchanged.

Number of pens that each of them will have
= 92 u ÷ 2
= 46 u

Number of pens that Zara gives to Barbara
= 52 u - 46 u
= 6 u

6 u = 24

1 u = 24 ÷ 6 = 4

Total number of pens that three of them have
= 92 u + 13 u
= 105 u

Average number of pens that each of them have
= 105 u ÷ 3
= 35 u
= 35 x 4
= 140

Answer(s): 140