Erika, Fanny and Xandra shared $231 among themselves. Fanny and Xandra shared ²₇ of the money equally. After Fanny gave away some of her money to Erika, Xandra had 3 times as much money as Fanny. How much money did Fanny give to Erika?

	Fanny	Xandra	Erika	Total
Before	1x3 = 3 u	1x3 = 3 u	5x3 = 15 u	21 u
Change	- 2 u	No change	+ 2 u
After	1x1 = 1 u	3x1 = 3 u	17 u	21 u

Fanny and Xandra shared ²₇ of the money equally.

Fraction of the money that Fanny and Xandra each had
= ²₇ ÷ 2
= ²₇ x ¹₂
= ¹₇

The amount that Xandra had remains unchanged.  The amount that Xandra had is the unchanged quantity. Make the amount that Xandra had the same. LCM of 1 and 3 is 3.

The amount that Fanny and Xandra had at first is the same.

Total amount that they had at first
= 3 u + 3 u + 15 u
= 21 u

21 u = 231

1 u = 231 ÷ 21 = 11

Amount that Fanny gave to Erika
= 3 u - 1 u
= 2 u
= 2 x 11
= $22

Answer(s): $22