Respuesta :

Sudipti

Answer:

unknown numbers

Step-by-step explanation:

letters are used for unknown numbers

xenia168

Answer:

Step-by-step explanation:

2 [ x + ( x + 2y )] = 28

2x  + 2y = 14

x + y = 7

x = 7 - y

x ∈ ( 0 , 7 )

y ∈ ( 0 , 7 )