$1\dfrac{2}{3}+[0,25:(10,3-9,8)-\dfrac{3}{4}]$
$=\dfrac{5}{3}+[\dfrac{1}{4}:0,5-\dfrac{3}{4}]$
$=\dfrac{5}{3}+\dfrac{1}{4}:\dfrac{1}{2}-\dfrac{3}{4}$
$=\dfrac{5}{3}+\dfrac{1}{2}-\dfrac{3}{4}$
$=\dfrac{17}{12}$
$(\dfrac{5}{7}.0,6-5:3\dfrac{1}{2}).(40\%-1,4).(-2)^3$
$=(\dfrac{5}{7}.\dfrac{3}{5}-5:\dfrac{7}{2}).(\dfrac{40}{100}-\dfrac{7}{5}).(-8)$
$=(\dfrac{3}{7}-5.\dfrac{2}{7}).(\dfrac{2}{5}-\dfrac{7}{5}).(-8)$
$=(\dfrac{3}{7}-\dfrac{10}{7}).(-1).(-8)$
$=(-1).(-1).(-8)$
$=-8$
$B=\dfrac{13}{15}.0,25.3+(\dfrac{8}{15}-1\dfrac{19}{60}):1\dfrac{23}{24}$
$B=\dfrac{13}{15}.\dfrac{1}{4}.3+(\dfrac{8}{15}-\dfrac{79}{60}):\dfrac{47}{24}$
$B=\dfrac{13.1.3}{15.4}+\dfrac{-47}{60}.\dfrac{24}{47}$
$B=\dfrac{13}{20}+\dfrac{-2}{5}$
$B=\dfrac{1}{4}$
