If a - b = 3 and a2 + b2 = 29, find the value of ab?	Pick: A) 10 B) 12 C) 14 D) 17 E) 18

Rationale: "2 ab = ( a 2 + b 2 ) - ( a - b ) 2 = 29 - 9 = 20 ab = 10 a )"
Answer: A