Giải thích các bước giải :
`3)`
`a)-18 in N (S)`
`b)(-8)/13 in Q (Đ)`
`c)7/12 in Z (S)`
`d)0,15 cancelin Q (S)`
`->`Chọn `b)(-8)/13 in Q`
`4)(7-2/3-1/4)-(4/3-10/4)-(5/4-1/3)`
`=7-2/3-1/4-4/3+10/4-5/4+1/3`
`=7+(1/3-2/3-4/3)+(10/4-5/4-1/4)`
`=7-5/3+1`
`=8-5/3`
`=24/3-5/3`
`=19/3`
`=6(1)/3`