Your answer would be 7
To find the common difference, you would subtract any of the given numbers in the sequence by the number to it's left
For example:
-25 -(-32) = ?
or
-18 -(-25) = ?
etc...
We would be using -25 - (-32) for this. You would be adding in this case because a negative × a negative would give you a positive number
So your equation would look like this now:
-25+32= 7
When you solve it, you would get 7.
It would be positive because you are going from left to right in the sequences. In the sequence, from left to right, it is adding a positive number.
So the common difference would be 7.