a) 2/ 7 = 6/21
c) 18/15 + x = 4/15
x = 4/15 - 18/15
x = -14/15
vậy x =...
d) 2/3 : x + 5/2 = 4 1/2
2/3 : x + 5/2 = 9/2
2/3 : x = 9/2 - 5/2
2/3 : x = 2
x = 2/3 : 2
x = 1/3
vậy x =...
`a) (x)/(7)=(6)/(21)`
`=> x.21=7.6=42`
`=>x=42:21`
`=>x=2`
`b) (x-2)/(8)=(11)/(4)`
`=>(x-2).4=8.11=88`
`=>x-2=88:4`
`=>x-2=22`
`=>x=22+2`
`=>x=24`
`c) => x=(4)/(15)-(18)/(15)`
`=>x=(-14)/(15)`
`d) =>(2)/(3)x=(9)/(2)-(5)/(2)`
`=>(2)/(3)x=2`
`=>x=(2)/(6)=(1)/(3)`