Write an expression to represent the sum of three consecutive even numbers.

Even numbers are reppresented as 2n where n is an even number

consecutive even numbers are 2 apart (2,4,6,8 ...)

so sum of 3 is

the numbers are

2n, 2n+2, 2n+4

so the sum is 2n+2n+2+2n+4=6n+6