Giúp e vs e đg rất cần e dùng hết số điểm của e rr

`a) 2/3 - 5/7 . 14/25`

`= 2/3 - frac{5xx14}{7xx25}`

`=2/3 - 2/5`

`= 10/15 - 6/15`

`= 4/15`

`        `

`b) ( 4 - 5/12 ) : 3 + 7/36`

`= ( 48/12 - 5/12 ) : 3 + 7/36`

`= 43/12 : 3 + 7/36`

`= 43/12 xx 1/3 + 7/36`

`= 43/36 + 7/36`

`= 50/36 =25/18`

`          `

`c) 2/5 + 3/5 : ( 3/5 + (-2)/3 ) - 3 1/2`

`= 2/5 + 3/5 : ( 9/15 + (-10)/15 ) - 7/2`

 `= 2/5 + 3/5 : (-1)/15 - 7/2`

`= 2/5 + 3/5 xx (-15) - 7/2`

`= 2/5 + (-9) - 7/2`

`= 18/45 + (-405)/45 -7/2`

`= (-387)/45 - 7/2`

`= (-43)/5 - 7/2`

`= (-86)/10 - 35/10`

`= (-121)/10`

`            `

`d) 1,25 : 15/20 + ( 25% - 5/6 ) : 4 2/3`

`= 5/4 : 15/20 + ( 1/4 - 5/6 ) : 14/3`

`= 5/4 : 15/20 + (3/12- 10/12 ) : 14/3`

`= 5/4 : 15/20 + (-7)/12 : 14/3`

`= 5/4 : 3/4 + (-7)/12 : 14/3`

`= 5/4 xx 4/3 + (-7)/12 xx 3/14`

`= 5/3 + (-7)/12 xx 3/14`

`= 5/3 + (-1)/8`

`= 40/24 + (-3)/24`

`= 37/24`