Answer:
-12
Step-by-step explanation:
Let's call the unknown number x.
Then, six subtracted from one times a number is -18 can be written as
1x - 6 = -18
So, we can solve for x, adding 6 to both sides
x - 6 = -18
x - 6 + 6 = -18 + 6
x = -12
Therefore, the number is -12