A marketing firm determined that, of 200 households surveyed, 80 used neither Brand K nor Brand B soap, 60 used only Brand K soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 200 households surveyed used both brands of soap? Pick one.
A) 15  B) 20  C) 30  D) 40  E) 45
SOLUTION FOR SOAP K AN40 SOAP B   (40) 40
<result>D</result>
A marketing firm determined that, of 200 households surveyed, 80 used neither Brand K nor Brand B soap, 60 used only Brand K soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 200 households surveyed used both brands of soap?