27 h => 100 %
1 h => 100/27 %
25 h => 100*25/27 % $${\frac{{\mathtt{100}}{\mathtt{\,\times\,}}{\mathtt{25}}}{{\mathtt{27}}}} = {\frac{{\mathtt{2\,500}}}{{\mathtt{27}}}} = {\mathtt{92.592\: \!592\: \!592\: \!592\: \!592\: \!6}}$$
25 h entsprechen 92,59 %
Gruß radix !