$${\mathtt{12.5}} = {\mathtt{0.8}}{\mathtt{\,\times\,}}{\mathtt{x}} \Rightarrow {\mathtt{x}} = {\frac{{\mathtt{125}}}{{\mathtt{8}}}} \Rightarrow {\mathtt{x}} = {\mathtt{15.625}}$$12.5=0.8x
divide both sides by 0.8
