The sum of 3 consecutive integers------------is---------------------twice the smallest integer
--------x + (x+1) + (x+2)-------------------------equals--------------------2---times-------x
Rewrite the line above as 3x + 3 = 2x
3x + 3 - 2x = 2x - 2x
x + 3 = 0
Then:
x = -3
x+1 = -2
x+2 = -1
The sum of the 3 integers is then -6 which is indeed 2 times the smallest integer -3.
(Since all three integers are less than 0, the integer with the greatest absolute value
or distance from 0 on the number line is the smallest integer.)