first off, let's convert the mixed fraction to improper fraction and then to a decimal and then multiply by 100.
[tex]\stackrel{mixed}{12\frac{7}{10}}\implies \cfrac{12\cdot 10+7}{10}\implies \stackrel{improper}{\cfrac{127}{10}}\implies \stackrel{to~decimal}{12.7}\implies 12.7(100)\implies \stackrel{to~percentage}{1270~\%}[/tex]