90% of Yen's amount was $4140 more than Dylan's amount. When Yen spent 65% of her amount and Dylan spent 10% of his amount, they had the same amount of amount left. Find the amount that Dylan had at first.

	90% of Yen's amount	Yen's amount	Dylan's amount
Before	162 u	180 u	70 u
Change		- 117 u (- 65%)	- 7 u (- 10%)
After		63 u	63 u

Percentage of Yen's amount left
= 100% - 65%
= 35%

Percentage of Dylan's amount left
= 100% - 10%
= 90%

35% = ³⁵₁₀₀ = ⁷₂₀
90% = ⁹⁰₁₀₀ = ⁹₁₀

The amounts of amount that Yen and Dylan had left were the same.
Make the numerators the same.

⁷₂₀ of Yen's amount = ⁹₁₀ of Dylan's amount
⁶³₁₈₀ of Yen's amount = ⁶³₇₀ of Dylan's amount

Amount that Yen had = 180 u

90% of the amount that Yen had
= 180 u x 90%
= 180 u x ⁹⁰₁₀₀
= 162 u

Difference between 90% of Yen's amount and Dylan's amount
= 162 u - 70 u 
= 92 u

92 u = 4140
1 u = 4140 ÷ 92 = 45

Amount that Dylan had at first
= 70 u
= 70 x 45
= $3150

Answer(s): $3150