Answer:
Let x = the first class
Let x +2 = the second class
Let x + 4 = the third class
x + (x + 2) + (x +4) or
x + x +2 + x + 4
3x + 6
Explanation:
Consecutive just means in order
integers are the whole numbers 0,1,2,3... and their opposites ...-3,-2,-1.
Think of any even integer. Let's use 12, for example, what would be the next even integer? 14. And the next? 16.
The second integer is 2 more than the first integer. The third integer is 4 more than the first.