90% of Kathy's amount was $1036 more than Oliver's amount. When Kathy spent 65% of her amount and Oliver spent 20% of his amount, they had the same amount of amount left. Find the amount that Oliver had at first.

	90% of Kathy's amount	Kathy's amount	Oliver's amount
Before	72 u	80 u	35 u
Change		- 52 u (- 65%)	- 7 u (- 20%)
After		28 u	28 u

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

Percentage of Oliver's amount left
= 100% - 20%
= 80%

35% = ³⁵₁₀₀ = ⁷₂₀
80% = ⁸⁰₁₀₀ = ⁴₅

The amounts of amount that Kathy and Oliver had left were the same.
Make the numerators the same.

⁷₂₀ of Kathy's amount = ⁴₅ of Oliver's amount
²⁸₈₀ of Kathy's amount = ²⁸₃₅ of Oliver's amount

Amount that Kathy had = 80 u

90% of the amount that Kathy had
= 80 u x 90%
= 80 u x ⁹⁰₁₀₀
= 72 u

Difference between 90% of Kathy's amount and Oliver's amount
= 72 u - 35 u 
= 37 u

37 u = 1036
1 u = 1036 ÷ 37 = 28

Amount that Oliver had at first
= 35 u
= 35 x 28
= $980

Answer(s): $980