Answer:
$200.0 is the cost for installing a carpet for a room that measures 12.0 feet by 15.0 feet.
Explanation:
Length of the room = l = 15.0 ft = 
Width of the room = w = 12.0 ft = 
(1 yard = 3 feet)
Area of the room = l × w = 
Cost for installing a carpet for a room = $10 per square yard
Cost for installing a carpet for a room wit area 20.0 square yard :

$200.0 is the cost for installing a carpet for a room that measures 12.0 feet by 15.0 feet.
Answer:
Valence electrons or outer electrons are most important as they participate in bonding. The octet rule states that atoms gain, lose, or share valence electrons to have filled energy levels.. this gives atoms a stable configuration like that of the nearest noble gas.