Question

The rule for the number of fish in a home aquarium is 1 gallon of water for each inch of fish length. Marta's aquarium holds 33 gallons of water and Hank's aquarium hold 45 gallons of water. The aquarium holds two types of fish, fish A and fish B. If Marta bought 3 of fish A and 2 of fish B, and Hank bought 3 of fish A and 4 of fish B, how long is fish A and how long is fish B?

Answer 1

Answer:

• A: 7 inches
• B: 6 inches

Step-by-step explanation:

We can let the variables A and B stand for the length in inches of fish A and fish B, respectively.

If we assume each person bought fish having a total length of 1 inch per gallon of aquarium, then we can write equations ...

... 3A +2B = 33 . . . . . total length of Marta's fish

... 3A +4B = 45 . . . . . total length of Hank's fish

Subtracting the first equation from the second, we get ...

... 2B = 12

... B = 6 . . . . . divide by 2

Using this value in the first equation, we have ...

... 3A + 2·6 = 33

... 3A = 21 . . . . . . . . subtract 12

... A = 7 . . . . . . . . . . divide by 3

Fish A is 7 inches long; fish B is 6 inches long.