Tổng hai phân số ban đầu là:

\(\dfrac{1}{5}+\dfrac{7}{9}=\dfrac{9}{45}+\dfrac{35}{45}=\dfrac{44}{45}\)

`3/4+2/5+3/12`

`=3/4+3/12+2/5`

`=9/12+3/12+2/5`

`=12/12+2/5`

`=1+2/5`

`=7/5`

`5/12+1/2+2/3+3/4`

`=5/12+6/12+8/12+9/12`

`=28/12=7/3`

5/12 +1/2 + 2/3 + 3/4

=5/12+6/12+8/12+9/12

=28/12=7/3

`1/4=(1xx5)/(4xx5)=5/20`

`2/5=(2xx4)/(5xx4)=8/20`

`3/2=(3xx10)/(2xx10)=30/20`

`1/3 = 44 : x/66`

`=> 44 : x/66 =1/3`

`=> x/66 = 44 : 1/3`

`=> x/66 = 44  xx 3`

`=>x/66= 132`

`=> x= 132 xx 66`

`=>x=8712`

8712 nha

44 : x/66 = 1/3

       x/66 = 44 : 1/3

       x/66 = 132

       x        =132×66

       x        =8712

`3-5/3`

`=3/1-5/3`

`=9/3-5/3`

`=4/3`

`15/7-2`

`=15/7-2/1`

`=15/7-14/7`

`=1/7`

3 - 5/3

=3/1 - 5/3 = 9/3 - 5/3

= 4/3

15/7 - 2

= 15/7 - 2/1 = 15/7 - 14/7

= 1/7

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tick đúng cho mình nha, chúc cậu học tốt

khong ghi duoc dau len tu dich nhe 

goi canh vuon hoa la x 

theo bai ra ta co 3x=4(x-3)

                          3x=4x-12

                          3x-4x=-12

                         -x=-12

                         x=12

vay chu vi tam giac deu la 36m

dien tich vuon rau la 81m²

`3-5/8`

`=3/1-5/8`

`=24/8-5/8`

`=19/8`

2

`1/3+1/4+2/5+2/3+3/4+3/5`

`=(1/3+2/3)+(1/4+3/4)+(2/5+3/5)`

`=1+1+1`

`=3`

giúp mình với đi ạ :{