e) \(40\%\times\left(3\dfrac{1}{4}+2\dfrac{4}{5}\div0,8\right)\)
\(=\dfrac{2}{5}\times\left(\dfrac{13}{4}+\dfrac{14}{5}\div0,8\right)\)
\(=\dfrac{2}{5}\times\dfrac{27}{4}\)
\(=\dfrac{27}{10}\)\(=2.7\)
270 sai rồi \(40\text{%}\) 1 là đổi ra \(\dfrac{2}{5}\)
2 là đổi sang 0,4
40% x(\(\dfrac{13}{4}\)+\(\dfrac{14}{5}\):0.8)
=40%x6.75
=270