[tex]\displaystyle 1)5*6+5*7=5(6+7)=5*13=65\\\\2)14*17+7*3-7*8=238+21-56=203\\\\3)\frac{1}{5}*31+30:5=\frac{31}{5}+6=\frac{61}{5}=12\frac{1}{5}=12,2[/tex]