What is the perimeter of triangle ABC ? (1) AB = 16 inches (2) ABC is

Target question: What is the perimeter of triangle ABC ?

Statement 1: AB = 16 inches
We now know the length of ONE side of the triangle.
Since we don't know the lengths of the other two sides, we cannot determine the perimeter of triangle ABC
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: ΔABC is equilateral.
This tells us that all 3 sides have the SAME length. However, we know nothing about these lengths.
So, we COULD have a 1 x 1 x 1 triangle, in which case the perimeter = 3
We COULD also have a 10 x 10 x 10 triangle, in which case the perimeter = 30
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
Statement 2 tells us that all 3 sides have the SAME length
Statement 1 tells us that each side has length 16
So, the answer to the target question is the perimeter = 16 + 16 + 16 = 48
Since we can answer the target question with certainty, the combined statements are SUFFICIENT

Answer: C

Cheers,
Brent