A. 2 (6 + 3 + 4 + 7 + 5 + 3)
B. 6 (3 + 4) + 7 (5 + 3) + 2
C. 2 [6 (3 + 4) + 7 (5 + 3)]
D. 6 [(3 + 4) + 2] + 7 [(5 + 3) + 2]
