Question

Write an expression to represent the sum of three consecutive even numbers. Let C represent the first number in the series

Answer 1

Let, the first number = C
second number will be = C + 2   ['cause next will be odd so we can't include that]
Third number = C + 4

Now, their sum would be:
C + C+2 + C+4 = 3C + 6

In short, Your Answer would be 3C + 6

Hope this helps!

Answer 2

Consecutive even integers would differ by 2.

So if the first even integer is C,

The next is C + 2

The next after is C + 2 + 2 = C + 4

The sum of the three consecutive integers =  C + (C + 2) + (C + 4)

 C + C + 2 + C + 4

C + C + C + 2 + 4

3C + 6

Sum = 3C + 6

Hope this helps.