a,3/2.7/3+14/3.1/2 b,1/9.145-13/3.2/145+2/145 c,(-31/12):15/7-1/18:15/7+20/9:15/7 d,7/80;(-7/3)-2/9:(8-8/3)-5/24.(-10/3+38/15)

Đáp án:a)35/6,       b)4193/261           c)-7/36               d)7/80

Giải thích các bước giải:

a)3/2.7/3+14/3.1/2

=7/2+7/3

=21/6+14/6

=35/6

b)1/9.145-13/3.2/145+2/145

=145/9-2/145(13/3-1)

=145/9-2/145.10/3

=145/9-4/87

=4205/261-12/261

=4193/261

c)(-31/12):15/7-1/18:15/7+20/9:15/7

=((-31/12)-1/18+20/9):15/7

=((-93/36-2/36+80/36).7/15

=(-5/12).7/15

=-7/36

d),7/80;(-7/3)-2/9:(8-8/3)-5/24.(-10/3+38/15)

=7/80.(-3/7)-2/9:(24/3-8/3)-5/24.(-50/15+38/15)

=(-3/80)-2/9:16/3-5/24.4/5

=(-3/80)-2/9.3/16-(-1/6)

=(-3/80)-1/24-(-1/6)

=(-9/240)-10/240-(-40/240)

=7/80