Respuesta :

Answer:

$1200

Step-by-step explanation:

 

S + C = 1200

 

S = C + 900

 

C + 900 + C = 1200

 

2C + 900 = 1200

 

2C = 300

 

C = 150

 

The chair costs $150. The sofa is $1050.

Together they cost $1200.