Seth, Daniel, Sam and Simon went shopping with a total of $855. After shopping, they had a total of $137 left. Daniel spent $20. The amount Sam spent was ²₃ the amount spent by Seth. The total amount spent by Seth and Daniel was $576 less than the total amount spent by Sam and Simon. How much did Seth and Simon spend altogether?

	Seth	Daniel	Sam	Simon	Total
Before					$855
Change	- 3 u	- $20	- 2 u	- ?	- $718
After					$137

Total amount that Seth, Daniel, Sam and Simon spent
= 855 - 137
= $718

Total amount that Seth and Daniel spent
= 3 u + 20

Total amount that Sam and Simon spent
= 3 u + 20 + 576
= 3 u + 596 

Total amount that Seth, Daniel, Sam and Simon spent
= 3 u + 20 + 3 u + 596
= 6 u + 616 

6 u + 616 = 718
6 u = 718 - 616
6 u = 102 

1 u = 102 ÷ 6 = 17

Total amount that Daniel and Sam spent
= 2 u + 20
= 2 x 17 + 20
= 34 + 20
= $54

Total amount that Seth and Simon spent
= 718 - 54
= $664

Answer(s): $664