80% of Sarah's amount was $160 more than Ben's amount. When Sarah spent 60% of her amount and Ben spent 30% of his amount, they had the same amount of amount left. Find the amount that Ben had at first.

	80% of Sarah's amount	Sarah's amount	Ben's amount
Before	28 u	35 u	20 u
Change		- 21 u (- 60%)	- 6 u (- 30%)
After		14 u	14 u

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

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

40% = ⁴⁰₁₀₀ = ²₅
70% = ⁷⁰₁₀₀ = ⁷₁₀

The amounts of amount that Sarah and Ben had left were the same.
Make the numerators the same.

²₅ of Sarah's amount = ⁷₁₀ of Ben's amount
¹⁴₃₅ of Sarah's amount = ¹⁴₂₀ of Ben's amount

Amount that Sarah had = 35 u

80% of the amount that Sarah had
= 35 u x 80%
= 35 u x ⁸⁰₁₀₀
= 28 u

Difference between 80% of Sarah's amount and Ben's amount
= 28 u - 20 u 
= 8 u

8 u = 160
1 u = 160 ÷ 8 = 20

Amount that Ben had at first
= 20 u
= 20 x 20
= $400

Answer(s): $400