x-9=-18
$${\mathtt{x}} = -{\mathtt{9}}$$
$${\mathtt{\,-\,}}{\mathtt{9}}{\mathtt{\,-\,}}{\mathtt{9}} = -{\mathtt{18}}$$
the number is -9
x-9=-18
$${\mathtt{x}} = -{\mathtt{9}}$$
$${\mathtt{\,-\,}}{\mathtt{9}}{\mathtt{\,-\,}}{\mathtt{9}} = -{\mathtt{18}}$$
the number is -9