First way: without using algebra (but your teacher won't
accept it!).
There are 3 of them so they must be right around 1/3 of -36,
which is -12, so the integers are -12, 2 less and 2 more than -12,
so the answer is -14, -12, and -10, and the smallest is -14.
Using algebra (which your teacher will accept):
n = smallest even integer
n+2 = middle-sized integer
n+4 = largest even integer
n + (n+2) + (n+4) = -36
Solve that for n. You'll get -14
Edwin