Let the unknown number be .
Then the opposite of this unknown number will be .
It is given to us in the question that when this unknown number, is increased by 9, or in other words when 9 is added to this unknown number,
, then this becomes 5 times it's opposite, which is
.
Thus, from the given condition in the question, the equation we get is as:
We will solve this by isolating as:
Thus the required number is -1.5
