dấu chấm là nhân nha
\(c,=\dfrac{13}{5}:\dfrac{9}{4}+\dfrac{5}{2}=\dfrac{13}{5}\cdot\dfrac{4}{9}+\dfrac{5}{2}=\dfrac{52}{45}+\dfrac{5}{2}=\dfrac{104}{90}+\dfrac{225}{90}=\dfrac{329}{90}\\ d,=\dfrac{57}{10}+\dfrac{3}{10}\cdot\left(\dfrac{9}{10}-\dfrac{1}{10}\right)=\dfrac{57}{10}+\dfrac{3}{10}\cdot\dfrac{4}{5}\\ =\dfrac{57}{10}+\dfrac{6}{25}=\dfrac{285}{50}+\dfrac{12}{50}=\dfrac{297}{50}\)
`2 3/5 : 2 1/4 + 5/2`
`= 13/5 : 9/4 + 5/2`
`= 13/5 xx 4/9 + 5/2`
`= 52/45 + 5/2`
`= 329/90`
________________________________________
`5 7/10 + 3/10 xx 9/10 - 1/10 xx 3/10`
`= 57/10 + 3/10 xx(9/10 - 1/10)`
`= 57/10 + 3/10 xx 4/5`
`= 57/10 + 6/25`
`= 297/50`
C) \(\dfrac{329}{90}\)
D) \(\dfrac{297}{50}\)
