If 10 is added to thrice a number and this sum is multiplied by 5, the result is the same as if the number is multiplied by 5 and 13 is added to the product. What is the number?
Choose one:
A) - 3.5 B) - 3.7 C) - 5 D) - 9 E) 11

Rationale: "let the number be x ; 5 ( 10 + 3 x ) = 5 x + 13 ; x = - 3.7 answer : b"
Answer: B