Sum of the squares of 3 no.'s is 179 and the sum of their products taken two at a time is 131. Find the sum? Choices: A) 20 B) 21 C) 26 D) 28 E) 30

Rationale: "( a + b + c ) 2 = a 2 + b 2 + c 2 + 2 ( ab + bc + ca ) = 179 + 2 * 131 a + b + c = √ 441 = 21 b"
Answer: B