what is 20.25+b square=169

$${\mathtt{20.25}}{\mathtt{\,\small\textbf+\,}}{{\mathtt{b}}}^{{\mathtt{2}}} = {\mathtt{169}}$$

$${{\mathtt{b}}}^{{\mathtt{2}}} = {\mathtt{169}}{\mathtt{\,-\,}}{\mathtt{20.25}}$$      

  b =$${\sqrt{{\mathtt{169}}{\mathtt{\,-\,}}{\mathtt{20.25}}}} = {\mathtt{12.196\: \!310\: \!917\: \!650\: \!468}}$$

Gruß radix !