Xandra had $400 less than Elijah. Elijah spent 0.8 of his money and Xandra spent 0.3 of her money. In the end, Elijah and Xandra had the same amount of money left. Find the amount of money Xandra had at first.

	Xandra	Elijah	Difference
Before	10 u	35 u	25 u
Change	- 1 u	- 7 u
After	7 u	7 u

0.8 = ⁴₅

Fraction of Elijah's amount left
= 1 - ⁴₅
= ¹₅

0.3 = ³₁₀

Fraction of Xandra's amount left
= 1 - ³₁₀
= ⁷₁₀

The amount that Elijah and Xandra each had in the end is the same. Make the numerators the same. LCM of 1 and 7 is 7.

¹₅ of Elijah's amount = ⁷₁₀ of Xandra's amount
⁷₃₅ of Elijah's amount = ⁷₁₀ of Xandra's amount

Amount that Xandra had less than Elijah
= 35 u - 10 u
= 25 u

25 u = 400

1 u = 400 ÷ 25 = 16

Amount that Xandra had at first
= 10 u
= 10 x 16
= $160

Answer(s): $160