The total cost of 3 jackets and 3 sweaters was $141. Tina bought 5 such jackets, 3 such sweaters and a cardigan for $248. If the total cost of a dress and a jacket was $70, find the difference in cost between the jacket and the dress.
Let 1 J be 1 jacket.
Let 1 S be 1 sweater.
Let 1 D be 1 dress.

3 J + 3 S = 141 --- (1)

1 J + 1 S = 141 ÷ 3
1 J + 1 S = 47 --- (2)

1 J + 1 D = 70 --- (3)

5 J + 3 S + 1 D = 248 --- (4)

(4) - (1)
(5 J + 3 S + 1 D) - (3 J + 3 S) = 248 - 141 
5 J - 3 J + 3 S - 3 S + 1 D = 107

2 J + 1 D = 107 --- (5)

(5) - (3)
(2 J + 1 D) - (1 J + 1 D) = 107 - 70
2 J - 1 J + 1 D - 1 D = 37
2 J - 1 J = 37

1 J = 37

From (3)
1 J + 1 D = 70
37 + 1 D = 70

1 D = 70 - 37 = 33

Difference in the cost between the jacket and the dress
= 1 J - 1 D
= 37 - 33
= $4

Answer(s): $4