a) (976 + 865) + 135 =976 + (865 + 135)=976 +1000=1976
891 + (799 + 109) =891 + 799 + 109=(891+109)+799=1000+799=1799
b) (2/5 + 7/9) + 3/5 =2/5+7/9+3/5= 2/5+3/5+7/9 = 1+7/9 = 16/9
19/11 + ( 8/13 + 3/11) =(19/11 + 3/11)+ 8/13=2 +8/13=34/13
c) 16,88 + 9,76 + 3,12 =(16,88 + 3,12)+ 9,76 =20+ 9,76=29,76
72,84 +17,16 + 82,84 =(72,84 +17,16) + 82,84 =90+82,84=172,84
d) 0,25 x 5,87 x 40 = (0,25 x 40)x 5,87 =10 x5,87=58,7
7,48 + 7,48 x 99 =7,48 + 740,52 =748
Vote cho ci nhé e!!!