1/12*8/9*8/4、(1/14+2/7)*7/8、19*(1/2-7/19)、4/5-1/3*3/4、26+1/5*1/3、(4/5-2/3)15/2

1/12*8/9*8/4
=2/27*2
=4/27
(1/14+2/7)*7/8
=1/14*7/8+2/7*7/8
=1/16+1/4
=5/16
19*(1/2-7/19)
=19*1/2-19*7/19
=9.5-7
=2.5
4/5-1/3*3/4
=4/5-1/4
=11/20
26+1/5*1/3
=26+1/15
=26又1/15
(4/5-2/3)*15/2
=4/5*15/2-2/3*15/2
=6-5
=1