40% of Erika's amount was $3604 less than Fred's amount. When Erika spent 35% of her amount and Fred spent 70% of his amount, they had the same amount of amount left. Find the amount that Fred had at first.

	Erika	Fred
Before	60 u	130 u
Change	- 21 u	- 91 u
After	39 u	39 u

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

Percentage of Fred's amount left
= 100% - 70%
= 30%

65% = ⁶⁵₁₀₀ = ¹³₂₀
30% = ³⁰₁₀₀ = ³₁₀

The amounts of amount that Erika and Fred had left were the same. Make the numerators the same.

¹³₂₀ of Erika's amount = ³₁₀ of Fred's amount
³⁹₆₀ of Erika's amount = ³⁹₁₃₀ of Fred's amount

Amount that Erika had = 60 u

40% of the amount that Erika had
= 40% x 60 u
= ⁴⁰₁₀₀ x 60 u
= 24 u

Difference between Fred's amount and 40% of Erika's amount
= 130 u - 24 u
= 106 u

106 u = 3604

1 u = 3604 ÷ 106 = 34

Amount that Fred had at first
= 130 u
= 130 x 34
= $4420

Answer(s): $4420