If x is an even integer represent the next 3 even integer.

If x is even, say it's 2. Then what do you need to get to the next even integer (4) ? You need to + 2. So it would be x + 2, x + 4 and x + 6.

Or, it could be x multiplied. I. e. 2x = 4, 3x = 6, and so on so forth.