system for summarized cost rate

$${\mathtt{25}}{\mathtt{\,\times\,}}{\mathtt{x}} = {\mathtt{0.004\: \!2}}{\mathtt{\,\times\,}}{\mathtt{y}}$$

$${\mathtt{25}}{\mathtt{\,\times\,}}{\mathtt{x}} = {\mathtt{0.008}}{\mathtt{\,\times\,}}{\mathtt{y}}$$

$${\mathtt{25}}{\mathtt{\,\times\,}}{\mathtt{x}} = {\mathtt{0.012\: \!1}}{\mathtt{\,\times\,}}{\mathtt{y}}$$