Đáp án:
$E=\dfrac{22}{45}$
Giải thích các bước giải:
$E=\dfrac{13}{30}+\dfrac{28}{45}.\dfrac{5}{2}-\left [ \left ( \dfrac{1}{2}+\dfrac{1}{3} \right ):\dfrac{53}{90} \right ]:\dfrac{50}{53}\\
=\dfrac{13}{30}+\dfrac{2.14}{5.9}.\dfrac{5}{2}-\left [ \left ( \dfrac{1}{2}+\dfrac{1}{3} \right ).\dfrac{90}{53} \right ].\dfrac{53}{50}\\
=\dfrac{13}{30}+\dfrac{14}{9}- \left ( \dfrac{3}{6}+\dfrac{2}{6} \right ).\dfrac{90}{53} .\dfrac{53}{50}\\
=\dfrac{13}{30}+\dfrac{14}{9}- \dfrac{5}{6}.\dfrac{9}{5} \\
=\dfrac{13}{30}+\dfrac{14}{9}- \dfrac{3}{2} \\
=\dfrac{13.3}{90}+\dfrac{14.10}{90}- \dfrac{45.3}{45.2} \\
=\dfrac{39+140-135}{90}\\
=\dfrac{44}{90}\\
=\dfrac{22}{45}$
