Repede vă rog dau coroana

Răspuns:
15/13·[9/10-1/13(⁵⁾25/12-³⁾17/20-⁴⁾12/15)]=
15/13·[9/10-1/13(125/60-51/60-48/60)]=
15/13·[9/10-1/13·26/60]=
15/13·(⁶⁾9/10-2/60)=
15/13·(54/60-2/60)=
15/13·52/60=13/13=1