Answer:

Step-by-step explanation:
Let the numbers be x and y
<h3>Given condition:</h3>
x + y = 48 --------(1)
y = 7x -------------(2)
Put Eq. (2) in (1)
x + 7x = 48
8x = 48
Divide 8 to both sides
x = 48/8
<h3>x = 6</h3>
Put x = 6 in Eq. (2)
y = 7 (6)
<h3>y = 42</h3>
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I wrote answers in picture and I use Desmos app to solve this equations
Answer:
The number of each kind of apartment in the building is 130 .
Step-by-step explanation:
Given as :
The total number of floor in a building = 15
The number of apartment on each floor = 26
So, The total number of apartment = 26 × 15 = 390
The number of kinds of apartment in the building is 3 , i.e 1-bedroom , 2-bedroom , 3-bedroom
Let The number of each kind of apartment in building = x
So, According to question
The number of each kind of building = 
or, x = 
∴ x = 130
Hence The number of each kind of apartment in the building is 130 . Answer