Question

В зоомагазине было 8 гуппи и 24 моллинезии.Шура купил половину моллинезий и 3 гуппи за 81 рубль,а остальных рыбок купил Дима за 87 рублей.Сколько стоила каждая рыбка?

Answer 1

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Answer 2

1)24:2=по12 моллинезии купили мальчики
2)8-3=5 гуппи купил Дима 
3)3 гуппи+12 моллинезии=81 руб
4)5 гуппи+12 моллинезии=87 руб
5)87-81=6 руб стоит 2 гуппи
6)6:2=3 рубля стоит 1 гуппи 
7)5*3=15 рублей стоят гуппи, которые купил дима
8)87-15=72 рубля потратил на моллинезии
9)72:12=6 рублей стоит 1 молонезия
Ответ: 3 рубля стоит одна гуппи, моллинезия стоит 6 рублей

Answer 3

Problem Analysis

We are given that there were 8 guppies and 24 mollies in a pet store. Shura bought half of the mollies and 3 guppies for 81 rubles, while Dima bought the remaining fish for 87 rubles. We need to determine the cost of each fish.

Solution

Let's assume the cost of each guppy is x rubles and the cost of each molly is y rubles.

From the given information, we can form the following equations:

1. Shura bought half of the mollies and 3 guppies for 81 rubles: - (1/2) * 24y + 3x = 81

2. Dima bought the remaining fish for 87 rubles: - (1/2) * 24y + (8 - 3) * x = 87

Simplifying the equations:

1. (1/2) * 24y + 3x = 81 - 12y + 3x = 81 - 4y + x = 27 -- Equation 1

2. (1/2) * 24y + 5x = 87 - 12y + 5x = 87 -- Equation 2

We now have a system of two equations with two variables. We can solve this system to find the values of x and y.

Solving the system of equations:

Multiply Equation 1 by 5 and Equation 2 by 4 to eliminate the x term:

5(4y + x) = 5(27) 4(12y + 5x) = 4(87)

Simplifying:

20y + 5x = 135 48y + 20x = 348

Multiply Equation 1 by 4 and Equation 2 by 5 to eliminate the y term:

4(4y + x) = 4(27) 5(12y + 5x) = 5(87)

Simplifying:

16y + 4x = 108 60y + 25x = 435

Now we have a new system of equations:

20y + 5x = 135 -- Equation 3 60y + 25x = 435 -- Equation 4

Subtract Equation 3 from Equation 4 to eliminate the y term:

(60y + 25x) - (20y + 5x) = 435 - 135 40y + 20x = 300 4y + 2x = 30 -- Equation 5

Divide Equation 5 by 2:

2y + x = 15 -- Equation 6

Now we have a new system of equations:

4y + x = 27 -- Equation 1 2y + x = 15 -- Equation 6

Subtract Equation 6 from Equation 1 to eliminate the x term:

(4y + x) - (2y + x) = 27 - 15 2y = 12 y = 6

Substitute the value of y into Equation 6 to find x:

2(6) + x = 15 12 + x = 15 x = 15 - 12 x = 3

Therefore, each guppy costs 3 rubles and each molly costs 6 rubles.

Answer

Each guppy costs 3 rubles and each molly costs 6 rubles.