Abi bought some rings and necklaces for her friends. The price of each ring was $3.90 while the price of each necklace was $13.50. For every 7 necklaces bought, she was given one such ring for free. After receiving the free rings, the number of rings was ¹₅ of the number of necklaces bought. If Abi paid a total of $2881.80, how much more did she pay for the necklaces than the rings?

Necklaces	Rings
5x7	1x7
Bought	Free	Bought
7x5	1x5
35 u	5 u	2 u

	Necklaces	Rings
	Bought	Free	Bought
Number	35 u	5 u	2 u
Value	$13.50	0	$3.90
Total value	472.5 u	0	7.8 u

The number of necklaces bought is the repeated identity. Make the number of necklaces bought the same.  LCM of 5 and 7 is 35.

Cost of the bought necklaces
= 35 u x 13.50
= 472.5 u

Cost of the bought rings
= 2 u x 3.90  
= 7.8 u

Total cost of the bought items
= 472.5 u + 7.8 u
= 480.3 u

480.3 u = 2881.80

1 u = 2881.80 ÷ 480.30 = 6

Amount that she paid more for the necklaces than the rings
= 472.5 u - 7.8 u 
= 464.7 u
= 464.7 x 6
= $2788.20

Answer(s): $2788.20