90% of Risa's amount was $3102 more than Rael's amount. When Risa spent 65% of her amount and Rael spent 35% of his amount, they had the same amount of amount left. Find the amount that Rael had at first.

	90% of Risa's amount	Risa's amount	Rael's amount
Before	234 u	260 u	140 u
Change		- 169 u (- 65%)	- 49 u (- 35%)
After		91 u	91 u

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

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

35% = ³⁵₁₀₀ = ⁷₂₀
65% = ⁶⁵₁₀₀ = ¹³₂₀

The amounts of amount that Risa and Rael had left were the same.
Make the numerators the same.

⁷₂₀ of Risa's amount = ¹³₂₀ of Rael's amount
⁹¹₂₆₀ of Risa's amount = ⁹¹₁₄₀ of Rael's amount

Amount that Risa had = 260 u

90% of the amount that Risa had
= 260 u x 90%
= 260 u x ⁹⁰₁₀₀
= 234 u

Difference between 90% of Risa's amount and Rael's amount
= 234 u - 140 u 
= 94 u

94 u = 3102
1 u = 3102 ÷ 94 = 33

Amount that Rael had at first
= 140 u
= 140 x 33
= $4620

Answer(s): $4620