14/5-(2.8-5/7)+2/7
=(2.8-2.8)+(5/7+2/7)
=0+1
=1
3/7-[19/5-(14/5+4/7)]
=3/7-(19/5-14/5-4/7)
=(3/7+4/7)-(19/5-14/5)
=1-1
=0
3/5÷[(1/5+1/3)÷2/9]
=3/5÷[8/15÷2/9]
=3/5×15/8×2/9
=1/4
14/5-(2.8-5/7)+2/7
=(2.8-2.8)+(5/7+2/7)
=0+1
=1
3/7-[19/5-(14/5+4/7)]
=3/7-(19/5-14/5-4/7)
=(3/7+4/7)-(19/5-14/5)
=1-1
=0
3/5÷[(1/5+1/3)÷2/9]
=3/5÷[8/15÷2/9]
=3/5×15/8×2/9
=1/4