y = -.156(30) + 13.348 is our problem.
First we multiply -.156 * 30
$${\mathtt{\,-\,}}\left({\mathtt{0.156}}{\mathtt{\,\times\,}}{\mathtt{30}}\right) = {\mathtt{\,-\,}}{\frac{{\mathtt{117}}}{{\mathtt{25}}}} = -{\mathtt{4.68}}$$
Then we add 13.348 to that product and the sum is our answer.