[tex]a+b+c= 786 \\\\ b-13= \frac{a}{2} \\\\ a= 2(b-13) \to 2b-26 \\\\\\ b=\frac{c}{4} \\\\ c=4b \\\\\\ 2b-26+b+4b=786 \\\\ 7b=786+26 \\\\ 7b=812 \ \ \ |:7 \\\\ \boxed{b=116} \\\\\\ a=2*116-26 \\\\ a=232-26 \\\\ \boxed{a=206} \\\\ c= 4*116 \\\\ \boxed{c=464}[/tex]