1/6x+5/12x=8,4 => 
\frac{7x}{12} = \frac{42}{5} => x= \frac{12*42}{5*7} = \frac{12*6}{5} = \frac{72}{5} =14,4" alt=" \frac{(2+5)x}{12} = \frac{84}{10} => \frac{7x}{12} = \frac{42}{5} => x= \frac{12*42}{5*7} = \frac{12*6}{5} = \frac{72}{5} =14,4" align="absmiddle" class="latex-formula">