Ủa có thấy gì đâu mà giúp?
\(\dfrac{9}{10}\times\dfrac{4}{5}+\dfrac{9}{10}:5+\dfrac{45}{10}+\dfrac{9}{10}\times4\)
\(=\left(\dfrac{9}{10}\times\dfrac{4}{5}+\dfrac{9}{10}\times\dfrac{1}{5}+\dfrac{9}{10}\times4\right)+\dfrac{45}{10}\)
\(=\dfrac{9}{10}\times\left(\dfrac{4}{5}+\dfrac{1}{5}+4\right)+\dfrac{9}{2}\)
\(=\dfrac{9}{10}\times5+\dfrac{9}{2}\)
\(=\dfrac{9}{2}+\dfrac{9}{2}\)
\(=\dfrac{18}{2}=9\)