B, because if I don't see a chart, I will have to assume that these people are at or are around 18 years of age.
-9 < 6 -v < 9 . . . . two inequalities
-15 < -v < 3 . . . . . subtract 6
-3 < v < 15 . . . . . . multiply by -1
Multiply:
64 squares 84 chess boards
---------------------- * ---------------------------- = 5376 squares
1 chess board 1
Barry = 92
heidi = h
92 = h + 18
92 - 18 = h + 18 - 18
74 = h
heidi has 74 marbles