A sum of money is sufficient to pay A's wages for 21 days and B's wages for 28 days. The same money is sufficient to pay the wages of both for? Choose the correct choice from the following answers:
A) 10 days  B) 12 days  C) 15 days  D) 20 days  E) 18 days
Let the total money be $x   A's 1 day work = $ x/21   12 days's 1 day work = $ x/28   A+12 days 1 day work = $ x/12   The money is sufficient to pay the wages of both for 12 days   Answer is 12 days
<result>B</result>
A sum of money is sufficient to pay A's wages for 21 days and B's wages for 28 days. The same money is sufficient to pay the wages of both for?