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Sheet # 87 Critical Thinking

Name: _____________________ Date_____________

Jose and David are analyzing their baseball-card collections. Jose has 3 Di-Maggio cards that are David's favorites. David has five Jeter cards that are Jose's favorites. They decide on two equal trades:

1) two Di-Maggio cards for three Jeter cards and \$1
2) three Di-Maggio cards and \$1 for five Jeter cards.

How much money do Jose and David think a Di-Maggio card worth? A Jeter card?

1) 2D = 3J + \$1

2) 3D + 1 = 5J

From equation # 1,

Equation # 1 can be written as after multiplying by 3 both sides

3) 6D = 9J +3

Equation #2 can be written as after multiplying by 2 both sides

4) 6D +2 = 10J

Substituting equation 3 into equation 4.

9J + 3 + 2 = 10J

So J = \$5

From Equation # 1, D = \$8

Jeter card = \$5

Di-Maggio card = \$8

Goldfish = G

Koi = K

G = K

Each Goldfish needs 12 inches x 2 gallons = 24 gallons

Each Koi needs 24 inches x 2 gallons = 48 gallons

1) 24G + 48K = 1000 gallons

Also number of Goldfish is equal to number of Koi fish. G = K

Using this and #1 equation

24G + 48G = 1000

72G = 1000

G = 13.88
K = 13.88

So number of Goldfish = 13.
Number of Koi fish = 13

If you use 14, the total amount of water will exceed 1000 gallons.