To set up consecutive even integers you use x for the first integer and x + 2 for the second integer. You add 2 since you are going to the next EVEN instead of just the next integer. Now we set up an equation = 798 and solve.
x + x + 2 = 798
2x + 2 = 798
subtract -2 from both sides
2x = 796
divide by 2 on both sides
x = 398
x + 2 = 398 + 2 = 400
CHECK 398 + 400 = 798