`@Thủy#Hoidap247`

$\text{Bài 1. Tính:}$

`3/5 + 7/5 = (3+7)/5 = 10/5 = 2/1 = 2.`

`9/15 + 4/15 = (9+4)/15 = 13/15.`

`7/16 - 1/16 = (7-1)/16 = 6/16 = 3/8.`

`9/4 - 3/4 = (9-3)/4 = 6/4 = 3/2.`

$\text{Bài 2. Tính:}$

`3/7 + 2/5 = 15/35 + 14/35 = (15+14)/35 = 29/.`

`3/25 + 7/5 = 3/25 + 35/25 = (3+35)/25 = 38/25.`

`3 + 3/7 = 21/7 + 3/7 = (21+3)/7 = 24/7.`

`7/8 + 1 = 7/8 + 8/8 = (7+8)/8 = 15/8.`

`9/4 - 7/16 = 36/16 - 7/16 = (36-7)/16 = 29/16.`

`11/5 - 5/8 = 88/40 - 25/40 = (88-25)/40 = 63/40.`

`3 - 7/4 = 12/4 - 7/4 = (12-7)/4 = 5/4.`

`22/3 - 4 = 22/3 - 12/3 = (22-12)/3 = 10/3.`

$\text{Bài 3. Rút gọn rồi tính:}$

`3/12 + 4/24 = 1/4 + 1/6 = 6/24 + 4/24 = 10/24 = 5/12.`

`15/25 + 6/18 = 3/5 + 1/3 = 9/15 + 5/15 = 14/15.`

`75/25 - 1/4 = 3 - 1/4 = 12/4 - 1/4 = 11/4.`

`11 - 22/44 = 11 - 1/2 = 22/2 - 1/2 = 21/2.`

$\text{Bài 4. Tìm}$ `x:`

`3/4 + x = 9/5`

          `x = 9/5 - 3/4`

          `x = 21/20.`

`x - 3/5 = 2 - 1/2`

`x - 3/5 = 3/2 `

`x`          `= 3/2 + 3/5`

`x`          `= 21/10.`

`11 - x = 3/7`

       `x = 11 - 3/7`

       `x = 74/7.`

`7/5 + x = 2 + 2/5`

`7/5 + x = 12/5`

          `x = 12/5 - 7/5`

          `x = 1.`

$\text{Bài 5. Tính:}$

`1/2 + 3/4 - 2/5 = 4/8 + 6/8 - 2/5 = 10/8 - 2/5 = 50/40 - 16/40 = 34/40 = 17/20.`

`7 - ( 3/5 + 3/10 ) = 7 - ( 6/10 + 3/10 ) = 7 - 9/10 = 70/10 - 9/10 = 61/10.`

`5 - 1/3 + 4/7 = 15/3 - 1/3 + 4/7 = 14/3 + 4/7 = 98/21 + 12/21 = 110/21.`

Chúc bạn học tốt !!! ^^

Bài 1 : Tính

3/5+7/5

=3+7/5

=10/5=2/1

9/15+4/15

=9+4/15

=13/15

7/16-1/16

=7-1/16

=6/16

9/4-3/4

=9-3/4

=6/4=3/2

Bài 1 nè bạn.