Let n represent the unknown numbers.
we add 2 and 4 to the numbers so that we are sure that they will be even
n + (n+2) + (n+4) = - 300 simplify
n + n + 2 + n + 4 = - 300
3n+6=-300
-6 -6
--------------- Get constants and variables to either side
3n = - 306
--- ------ Isolate the variables
3 3
n= - 102
Then plug this in for the above values
n+2= - 102+2= -100
n+4= - 102+4 = -98