Question

the sum of the first and third of three consecutive integers is 140. find the three even integers

Answer 1

68 70 72
Note that 68 + 72 equals 140.
You don't really need to use algebra to get this..just figure out which 2 numbers spaced 4 apart will sum to 140...by trial and error.
If you must use algebra let the 3 consecutive intertgers be
x , x + 2 , and x + 4
Now, x + (x + 4) = 140...you can get the answer that way too

Answer 2

ohhh. and i think you mean "3 consectutve even integers" in your 1st sentence to be consistent with your 2nd sentence. right?