2.4×9/7+4÷7/5
=12/5 ×9/7 +4×5/7
=108/35 +20/7
=108/35 +100/35
=208/35
=5又33/35
晕,难道2.4的2.指的是题号第2题?
4×9/7+4÷7/5
=4×9/7+4×5/7
=9×4/7+5×4/7
=(9+5)×4/7
=14×4/7
=8
2.4×9/7+4÷7/5
=2.4×9/7+4/7×1/5
=2.4×9×5/(7×5)+4/35
=108/35+4/35
=112/35
=3.2
2.4x9/7+4x5/7=1/7x(2.4+20)=22.4/7=3.2