(1)1.25*0.5*32
=1.25*0.5*(8*4)
=(1.25*8)*(0.5*4)
=10*2
=20
(2)5/7+9/8*5/9+3/8
=5/7+5/8+3/8
=5/7+(5/8+3/8)
=5/7+1
=12/7
(3)(3/7+5/14)/11/21-2/5
=(3/7)/(11/21)+(5/14)/(11/21)-2/5
=9/11+15/22-2/5
=3/2-2/5
=15/10-4/10
=11/10
(1)1.25*0.5*32
=1.25*0.5*(8*4)
=(1.25*8)*(0.5*4)
=10*2
=20
(2)5/7+9/8*5/9+3/8
=5/7+5/8+3/8
=5/7+(5/8+3/8)
=5/7+1
=12/7
(3)(3/7+5/14)/11/21-2/5
=(3/7)/(11/21)+(5/14)/(11/21)-2/5
=9/11+15/22-2/5
=3/2-2/5
=15/10-4/10
=11/10