1 . tính bằng hai cách
3/4 x 1/2 x 2
Cách 1 : ....................................................................................
Cách 2 : .....................................................................................
( 3/4+1/2 ) x 5/7
Cách 1 : ....................................................................................
Cách 2 : ....................................................................................
5/7 x 13/21 + 2/7 x 13/21
Cách 1 : ....................................................................................
Cách 2 : ....................................................................................
7/5 + 4/3 + 7/5 + 4/3
Cách 1 : ....................................................................................
Cách 2 : ....................................................................................