5/(4*9)+5/(9*14)+5/(14*19)+5/(19*24)+5/(24*29)+.....5/(39*44)+5/(44*49)=1/4-1/9+1/9-1/14+1/14-1/19+1/19-1/24+1/24-1/29+......+1/39-1/44+1/44-1/49=1/4-1/49=49/441-4/441=45/441=5/49
