80% of Sabrina's amount was $551 more than Bobby's amount. When Sabrina spent 65% of her amount and Bobby spent 20% of his amount, they had the same amount of amount left. Find the amount that Bobby had at first.

	80% of Sabrina's amount	Sabrina's amount	Bobby's amount
Before	64 u	80 u	35 u
Change		- 52 u (- 65%)	- 7 u (- 20%)
After		28 u	28 u

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

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

35% = ³⁵₁₀₀ = ⁷₂₀
80% = ⁸⁰₁₀₀ = ⁴₅

The amounts of amount that Sabrina and Bobby had left were the same.
Make the numerators the same.

⁷₂₀ of Sabrina's amount = ⁴₅ of Bobby's amount
²⁸₈₀ of Sabrina's amount = ²⁸₃₅ of Bobby's amount

Amount that Sabrina had = 80 u

80% of the amount that Sabrina had
= 80 u x 80%
= 80 u x ⁸⁰₁₀₀
= 64 u

Difference between 80% of Sabrina's amount and Bobby's amount
= 64 u - 35 u 
= 29 u

29 u = 551
1 u = 551 ÷ 29 = 19

Amount that Bobby had at first
= 35 u
= 35 x 19
= $665

Answer(s): $665