№414(а),415(а,б)

414(а):
\(1{,}02\cdot(3{,}785+1{,}217:0{,}2)-0{,}6434=1{,}02\cdot9{,}87-0{,}6434=9{,}424.\)

415(а):
\[ 2\tfrac17\left(2\tfrac13+2\tfrac{2}{15}\right)-8{,}8 =\frac{15}{7}\cdot\frac{67}{15}-\frac{44}{5} =\frac{27}{35}. \]

415(б):
\[ \left(2\tfrac23\cdot\frac38-0{,}12\cdot\frac12\right):0{,}4 =(1-0{,}06):0{,}4=2{,}35. \]