When a negative integer gets divided my another negative integer, it results in a positive number. This means that we can eliminate all the negative symbols in this problem
18/9 = 2
Now all is left to determine which other expression is equivalent to 2
In the expression -10 / 5, since there is only one negative symbol, the postulate for negative number division states that two negative integers makes a positive number, and there is one negative integer and one positive whole number.
18/2 = 9 = incorrect
12/3 = 4 = incorrect
-10/5 = -2 = incorrect
8/4 = 2 = correct
So the expression -8/-4 is equivalent to the expression -18/-9
