Mình học bài này tên là Assuming ở Stemhouse nhớ

A pig and a cow have 4 legs each and a chicken and ducks have 2 legs each.

The number of pigs and chickens:

90 : 2 = 45 ( pigs and chickens )

The number of legs of pigs and chickens:

256 : 2 = 128 ( legs )

The number of legs if all of them are chickens:

45 x 2 = 90 ( legs )

The difference between the original and new number:

128 - 90 = 38 

The difference between the number of legs a pig has and a chicken has:

4 - 2 = 2 ( legs )

The number of chickens: 

38 : 2 = 19 ( chickens )

The number of pigs:

45 - 19 = 26 ( pigs )

Ans: Pigs and cows: 26 each

       Chickens and ducks: 19 each

Wow, trùng hợp làm sao là mình đang làm bài này luôn 

A pig and a cow have 4 legs each and a chicken and ducks have 2 legs each.

The number of pigs and chickens:

                       90 : 2 = 45 ( pigs and chickens )

The number of legs of pigs and chickens:

                       256 : 2 = 128 ( legs )

The number of legs if all of them are chickens:

                        45 x 2 = 90 ( legs )

The difference between the original and new number:

                           128 - 90 = 38 

The difference between the number of legs a pig has and a chicken has:

                               4 - 2 = 2 ( legs )

The number of chickens: 

                               38 : 2 = 19 ( chickens )

The number of pigs:

                          45 - 19 = 26 ( pigs )

               Ans: Pigs and cows: 26 each

                    Chickens and ducks: 19 each