The product of a and b is equal to 10 more than twice the sum of a and b. If b = 9, what is the value of b - a?
Select the correct option:  A) 2  B) 5  C) 7  D) 24  E) 35

Rationale: "ab = 10 + 2 ( a + b ) 9 a = 10 + 2 a + 18 7 a = 28 a = 4 b - a = 9 - 4 = 5 b is the answer"
Answer: B