16/7-16/7*9/2
=16/7x(1-9/2 )
=16/7x(-7/2 )
=-8
(2)
99*1/100
=（100-1）*1/100
=100*1/100-1*1/100
=1-1/100
=99/100
（3）
13/20*99+13/20
= 13/20*(99+1)
= 13/20*100
=65第一道是7/16-7/16*2/9对不起写错了哈哈==7/16-7/16*2/9=7/16*（1-2/9）=7/16*7/9=49/144