A man sells a piece of cloth. On the first day, he sells one-fifth of the piece. On the second day he sells four-sevenths of the rest. There are 12 meters of cloth left. Answer below question : a, How long is the piece of cloth ? b, How many meter of cloth does he sell each day ?

Đáp án: a + b) there are 12m of cloth left so 2/7 ( 1 - 4/7 = 2/7 ) of the cloth he sells on the 2nd day = 12m
 Therefore -> 1/7 of the cloth he has remain on the 2nd day : 12 : 2 = 6m
                       7/7 of the cloth he has remain on the 2nd day : 6 x 7 = 42m

                       4/7 of the cloth he has remain on the 2nd day: 6x4 = 24m
                 So 42m is = to the length of 1/5 of the original cloth on the first day.
Therefore -> The length of the original cloth is : 42 : 1/5 = 210m

Conclusion : a) 210m
                    b) day 1: 42m
                         day 2: 24m
 

thanhvetranh##@

Đáp án: a + b) there are 12m of cloth left so 2/7 ( 1 - 4/7 = 2/7 ) of the cloth he sells on the 2nd day = 12m
 Therefore -> 1/7 of the cloth he has remain on the 2nd day : 12 : 2 = 6m
                       7/7 of the cloth he has remain on the 2nd day : 6 x 7 = 42m

                       4/7 of the cloth he has remain on the 2nd day: 6x4 = 24m
                 So 42m is = to the length of 1/5 of the original cloth on the first day.
Therefore -> The length of the original cloth is : 42 : 1/5 = 210m

Conclusion : a) 210m
                    b) day 1: 42m
                         day 2: 24m