Xandra's and Usha's savings were in the ratio of 4 : 7. Both of them shared the cost of their older sister's present equally. Xandra's remaining savings was ¹₅ as much as Usha's savings. What percentage of her savings did Xandra spend? Correct the answer to 1 decimal place.

	Xandra	Usha	Difference
Before	4x4 = 16 u	7x4 = 28 u	3x4 = 12 u
Change	- 13 u	- 13 u
After	1x3 = 3 u	5x3 = 15 u	4x3 = 12 u

Since Xandra and Usha shared the cost of their older sister's present equally, the amount each paid for the present is the same. 

So, the difference in the amounts between Xandra and Usha at first and in the end remains the same.  Make the difference in the amounts between Xandra and Usha at first and in the end the same. LCM of 3 and 4 is 12.

Amount that Xandra spent on the present
= 16 u - 3 u
= 13 u

Percentage of her savings that Xandra spent
= ¹³₁₆ x 100%
≈ 81.3%

Answer(s): 81.3%