The total cost of 8 skirts and 8 dresses was $504. Tina bought 10 such skirts, 8 such dresses and a cardigan for $619. If the total cost of a jacket and a skirt was $76, find the difference in cost between the skirt and the jacket.
Let 1 S be 1 skirt.
Let 1 D be 1 dress.
Let 1 J be 1 jacket.

8 S + 8 D = 504 --- (1)

1 S + 1 D = 504 ÷ 8
1 S + 1 D = 63 --- (2)

1 S + 1 J = 76 --- (3)

10 S + 8 D + 1 J = 619 --- (4)

(4) - (1)
(10 S + 8 D + 1 J) - (8 S + 8 D) = 619 - 504 
10 S - 8 S + 8 D - 8 D + 1 J = 115

2 S + 1 J = 115 --- (5)

(5) - (3)
(2 S + 1 J) - (1 S + 1 J) = 115 - 76
2 S - 1 S + 1 J - 1 J = 39
2 S - 1 S = 39

1 S = 39

From (3)
1 S + 1 J = 76
39 + 1 J = 76

1 J = 76 - 39 = 37

Difference in the cost between the skirt and the jacket
= 1 S - 1 J
= 39 - 37
= $2

Answer(s): $2