25/48= 54/12-58/25= 45/78:41/45= 4/5+12/78= je comprends pas ces fraction

25/48 = 0,53

54/12 - 58/25 =54*25/12*25 - 25*58/25*58 

= 1350/300  - 696/300

= 654/300 = 109*6 / 50*6

On enleve les deux 6 donc, 

= 109/50

45/78 : 41/45

45/78 * 45/41

2025/3198

= 675*3 / 1066*3 , on enleve les trois , donc 

= 675/1066

4/5 + 12/78

on fait : 4*78 / 5*78 + 12*5/75*5

312/390 + 60/390 = 372/390 = 62/65

Il faut juste que tu les réduits !

25/48=1*24/2*24=1/2

(54/12)-(58/25)= (6*9/6*2)-(58/25)

                        = (9/2)-(58-25)

                        = (9*12.5/2*12.5)-(58/25)

                        = (112.5/25)-(58/25)

                        = (54.5/25)

                        = (54.5*2/25*2)

                         109/50

etc ...