Răspuns: 1/20
Explicație pas cu pas:
2 4/5= (5*2+4)/5=14/5
2 14/20=(20*2+14)/20=54/20
1 3/25=(25*1+3)/25=28/25
inlocuiesc in ex si rezulta
14/5 *(54/20*20/63-28/30:28/25)=
14/5*(54/63-28/30*25/28)=
14/5*(6/7-25/30)=
14/5*(6/7-5/6)=
14/5*(6*6/42-5*7/42)=
14/5*(36/42-35/42)=14/5*1/42=14/42*5=1/4*5=1/20
