a,4,25 + 3,25 + 3,75 + 5,85=4,25 + 3,75 + 3,25 + 5,85 b,(3/5 + 4/7 ) + 2/5= (3/5 + 2/5) + 4/7
=8 + 3,25 + 5,85 =1 + 4/7
=11,25 + 5,85 =11/7
=17,1
c,6,24 + 5,36 + 3,76=6,24 + 3,76 + 5,36 d, (19/15 + 3/5) + 11/15=(19/15 + 11/15) + 3/5
=10 + 5,36 =2 + 3/5
=15,36 =13/5