80% of Fiona's amount was $144 more than Oscar's amount. When Fiona spent 60% of her amount and Oscar spent 35% of his amount, they had the same amount of amount left. Find the amount that Oscar had at first.

	80% of Fiona's amount	Fiona's amount	Oscar's amount
Before	52 u	65 u	40 u
Change		- 39 u (- 60%)	- 14 u (- 35%)
After		26 u	26 u

Percentage of Fiona's amount left
= 100% - 60%
= 40%

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

40% = ⁴⁰₁₀₀ = ²₅
65% = ⁶⁵₁₀₀ = ¹³₂₀

The amounts of amount that Fiona and Oscar had left were the same.
Make the numerators the same.

²₅ of Fiona's amount = ¹³₂₀ of Oscar's amount
²⁶₆₅ of Fiona's amount = ²⁶₄₀ of Oscar's amount

Amount that Fiona had = 65 u

80% of the amount that Fiona had
= 65 u x 80%
= 65 u x ⁸⁰₁₀₀
= 52 u

Difference between 80% of Fiona's amount and Oscar's amount
= 52 u - 40 u 
= 12 u

12 u = 144
1 u = 144 ÷ 12 = 12

Amount that Oscar had at first
= 40 u
= 40 x 12
= $480

Answer(s): $480