The total cost of 7 windbreakers and 7 jumpsuits was $462. Tina bought 9 such windbreakers, 7 such jumpsuits and a cardigan for $564. If the total cost of a blazer and a windbreaker was $64, find the difference in cost between the windbreaker and the blazer.
Let 1 W be 1 windbreaker.
Let 1 J be 1 jumpsuit.
Let 1 B be 1 blazer.

7 W + 7 J = 462 --- (1)

1 W + 1 J = 462 ÷ 7
1 W + 1 J = 66 --- (2)

1 W + 1 B = 64 --- (3)

9 W + 7 J + 1 B = 564 --- (4)

(4) - (1)
(9 W + 7 J + 1 B) - (7 W + 7 J) = 564 - 462 
9 W - 7 W + 7 J - 7 J + 1 B = 102

2 W + 1 B = 102 --- (5)

(5) - (3)
(2 W + 1 B) - (1 W + 1 B) = 102 - 64
2 W - 1 W + 1 B - 1 B = 38
2 W - 1 W = 38

1 W = 38

From (3)
1 W + 1 B = 64
38 + 1 B = 64

1 B = 64 - 38 = 26

Difference in the cost between the windbreaker and the blazer
= 1 W - 1 B
= 38 - 26
= $12

Answer(s): $12