Answer: 181
Explanation: First represent your 3 consecutive numbers as follows.
X ⇒ first number
X + 1 ⇒ second number
X + 2 ⇒ third number
Since their sum is 543, our equation reads x + (x + 1) + (x + 2) = 543.
Simplifying on the left side we have 3x + 3 = 543.
Subtracting 3 from both sides, we have 3x = 540.
Now dividing both sides by 3, we find that x = 180.
If x = 180, then x + 1 is 180 + 1 or 181 and x + 2 is 180 + 2 or 182.
This means that your second number would be 181.