Question

В жилом доме 215 квартир. Сколько из них 1 ком ?, если 3-ком на 10 меньше, чем 2-ком. и на 5 больше чем 1- комнатных.

Answer 1

х- однокомнатных

(х+5)- трехкомнатных

(х+5+10)=(х+15)-двухкомнатных

х+х+5+х+15=215

3х=215-20

3х=195

х=195/3=65 квартир однокомнатных 

Answer 2

Calculating the Number of 1-Bedroom Apartments in a Residential Building

To calculate the number of 1-bedroom apartments in the residential building, we can use the given information about the number of 3-bedroom and 2-bedroom apartments.

Given: - Total number of apartments: 215 - Number of 3-bedroom apartments: 10 less than the number of 2-bedroom apartments - Number of 2-bedroom apartments: 5 more than the number of 1-bedroom apartments

Let's denote: - Number of 1-bedroom apartments as x - Number of 2-bedroom apartments as y - Number of 3-bedroom apartments as z

We can express the given information in the form of equations: 1. x + y + z = 215 (total number of apartments) 2. z = y - 10 (number of 3-bedroom apartments is 10 less than the number of 2-bedroom apartments) 3. y = x + 5 (number of 2-bedroom apartments is 5 more than the number of 1-bedroom apartments)

We can solve these equations to find the values of x, y, and z.

First, let's express z in terms of x using equation (2): z = y - 10 y = z + 10

Now, substitute the value of y from equation (3) into equation (1): x + (x + 5) + (z + 10) = 215 2x + z + 15 = 215 2x + z = 200

We also know that z = y - 10 and y = x + 5, so we can substitute these into the equation: 2x + (x + 5) - 10 = 200 3x - 5 = 200 3x = 205 x = 205 / 3 x ≈ 68.33

Since the number of apartments must be a whole number, we can conclude that there are approximately 68 1-bedroom apartments in the residential building.

Conclusion

Based on the given information, there are approximately 68 1-bedroom apartments in the residential building.