\(7.5+\dfrac{21}{5}=35+\dfrac{21}{5}=\dfrac{175}{5}+\dfrac{21}{5}=\dfrac{196}{5}\)
7.5+\(\dfrac{21}{5}\)=35+\(\dfrac{21}{5}\)=\(\dfrac{35}{1}+\dfrac{21}{5}=\dfrac{175}{5}+\dfrac{21}{5}=\dfrac{196}{5}\)
bn nên ghi rõ dấy `,` nhé lớp `6` học `.` là nhân nhé bn ^^
`7,5 + 21/5`
`= 15/2 + 21/5`
`= 75/10 + 42/10`
`= (75 + 42)/10`
`= 117/10`