well, let's say 1 meter is the 100%, now, if we know that 1 is 100%, what percentage is 70?
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 1&100\\ 70&x \end{array}\implies \cfrac{1}{70}=\cfrac{100}{x}\implies x =7000[/tex]
