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

	Cindy	Michael	Difference
Before	10 u	35 u	25 u
Change	- 1 u	- 7 u
After	7 u	7 u

0.8 = ⁴₅

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

0.3 = ³₁₀

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

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

¹₅ of Michael's amount = ⁷₁₀ of Cindy's amount
⁷₃₅ of Michael's amount = ⁷₁₀ of Cindy's amount

Amount that Cindy had less than Michael
= 35 u - 10 u
= 25 u

25 u = 400

1 u = 400 ÷ 25 = 16

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

Answer(s): $160