I got 6.49204 but you will need to round so D 6.5
I added all of the numbers up
Fraction of girls = 1 - 3/7 = 4/7
4/7 is equivalent to 72 girls
1/7 .. .. ............. 72 / 4 = 18
Total number of children = 7/7 = 18*7 = 126 Answer
About $0.37 because you divide $4.49 by 12