1) (3/4+1/20)×1/2=(15+1/20)×1/2=16/20×1/2=
=4/5×1/2=4×1/5×1=4/5
2) (7/12-1/3)×16/19 =(7-4/12 )×16/19 =1/4×16/19=
=4/19
3) (7 3/5- 2 4/15)×9/32=(5 9-4/15)×9/32=
=5 1/3×9/32=16/3×9/32=3/2=1 1/2
4) (11/24+1/6)×1 3/5=(11+4/24)×18/5=
=15/24×18/5=9/4=2 1/4
5) (5 1/2+2 3/5)×5/9=( 7 5+6/10)×5/9=
=(7 11/10)×5/9=8 1/10×5/9=81/10×5/9=
=9/2=4 1/2
6) (7-2 5/16)×4/25 =(6 16/16-2 5/16)×4/25=
=(4 16-5/16)×4/25=4 11/16×4/25=
=75/16×4/25=3/4