Question

When a number is increased by 9 it is five times its opposite. Find the number.

Answer 1

Let the unknown number be $x$.

Then the opposite of this unknown number will be $-x$.

It is given to us in the question that when this unknown number, $x$ is increased by 9, or in other words when 9 is added to this unknown number, $x$, then this becomes 5 times it's opposite, which is $-x$.

Thus, from the given condition in the question, the equation we get is as:

$x+9=-5x$

We will solve this by isolating $x$ as:

$x+5x=-9$

$6x=-9$

$x=-\frac{3}{2} =-1.5$

Thus the required number is -1.5