No need to use your units in the equation, until you're finshed calculating.
$${\mathtt{3\,215.52}}{\mathtt{\,\times\,}}{\mathtt{50}} = {\mathtt{160\,776}}$$
$${\frac{{\mathtt{160\,776}}}{{\mathtt{1\,400}}}} = {\frac{{\mathtt{2\,871}}}{{\mathtt{25}}}} = {\mathtt{114.84}}$$
= 144,84 m3