Question

Помогите решить задачу:шлольный пенал дороже альбома в 3 раза.Пенал,карандаш и альбом стоят 400руб.сколько стоит пенал,если цена карандаша 40 руб? решение по действиям

Answer 1

1) 400-40=360 (р) - альбом и пенал
2) 360:3=120 (р) - альбом
3) 400-(120+40)=240 (р) - пенал

Answer 2

Problem Analysis

We are given that the cost of a pencil case (пенал) is three times the cost of an album (альбом). The total cost of a pencil case, pencil (карандаш), and album is 400 rubles. We need to find the cost of the pencil case if the pencil costs 40 rubles.

Solution Steps

Let's break down the problem into steps to find the solution:

1. Let's assume the cost of the album is x rubles. 2. According to the problem, the cost of the pencil case is three times the cost of the album. So, the cost of the pencil case would be 3x rubles. 3. We are given that the total cost of the pencil case, pencil, and album is 400 rubles. So, we can write the equation: x + 40 + 3x = 400. 4. Simplifying the equation, we get: 4x + 40 = 400. 5. Subtracting 40 from both sides of the equation, we get: 4x = 360. 6. Dividing both sides of the equation by 4, we get: x = 90. 7. Now, we can substitute the value of x back into the equation to find the cost of the pencil case: 3x = 3 * 90 = 270 rubles.

Therefore, the cost of the pencil case is 270 rubles.

Detailed Solution

Let's go through the solution steps in more detail:

1. Let's assume the cost of the album is x rubles. 2. According to the problem, the cost of the pencil case is three times the cost of the album. So, the cost of the pencil case would be 3x rubles. 3. We are given that the total cost of the pencil case, pencil, and album is 400 rubles. So, we can write the equation: x + 40 + 3x = 400. 4. Simplifying the equation, we get: 4x + 40 = 400. 5. Subtracting 40 from both sides of the equation, we get: 4x = 360. 6. Dividing both sides of the equation by 4, we get: x = 90. 7. Now, we can substitute the value of x back into the equation to find the cost of the pencil case: 3x = 3 * 90 = 270 rubles.

Therefore, the cost of the pencil case is 270 rubles.

Conclusion

The cost of the pencil case is 270 rubles.