0,7 +0,7 = 1,4 -> 100 %
1,3 +0,7 = 2 -> x % x =2*100/1,4 = 142,86 [%] (gerundet)
$${\frac{{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{100}}}{{\mathtt{1.4}}}} = {\frac{{\mathtt{1\,000}}}{{\mathtt{7}}}} = {\mathtt{142.857\: \!142\: \!857\: \!142\: \!857\: \!1}}$$
Gruß radix !