1. When completed, this crossnumber puzzle has exactly one digit in each box.
2. None of the a,b,c or d boxes (whether down or across) can contain any leading zero.
3. Both concatenations ab and cd consist of nonzero digits.

       +-----+-----+
       |  a  |  b  |
 +-----+-----+-----+
 |  c  |     |     |
 +-----+-----+-----+
 |  d  |     |      
 +-----+-----+


    ACROSS                                         DOWN                

a. Abigail's age                           a. Sum of three of the ages
                                             in c "across".
c. Sum of Abigail's age, 
Blanche's age, Cynthia's                   b. Cynthia's age.
age, and Darlene's age.                    
                                           c. Darlene's age.
d. Blanche's age