Ta có : \(a+a+a+\frac{1}{2}.\frac{2}{5}+a+\frac{8}{10}+a=136\)

        \(\Leftrightarrow5a+\frac{1}{2}.\frac{2}{5}+\frac{8}{10}=136\)

        \(\Leftrightarrow5a+\frac{1}{5}+\frac{8}{10}=136\)

         \(\Leftrightarrow5a+1=136\)

         \(\Leftrightarrow5a=135\)

          \(\Leftrightarrow a=27\)

Vậy \(a=27\)

a + a + a + 1/2 . 2/5 + a + 8/10 + a = 136

=> a + a + a + a + a + 1/2 . 2/5 + 4/5 = 136

=> 5a + 1/5 + 4/5 = 136

=> 5a + 1 = 136

=> 5a = 136 - 1

=> 5a = 135

=> a = 135 : 5

=> a = 27

đcm là đầu cắt moi

vì quá dễ nên mình không thể trả lời bạn được nhé!

dễ vl ko làm đc là ngu 

a + a + a + 1/2 × 2/5 + a + 8/10 + a = 136

5 × a + 1/5 + 4/5 = 136

5 × a + 1 = 136

5 × a = 136 - 1

5 × a = 135

a = 135 : 5

a = 27

a ) \(x+x+x+\frac{1}{2}\times\frac{2}{5}+x+\frac{1}{10}+x=136\)

                                                                \(5x+1=136\)

                                                                         \(5x=135\)

                                                                             \(x=27\)

b ) \(3\frac{1}{2}-x:\frac{3}{5}=\frac{3}{2}\)

                   \(x:\frac{3}{5}=2\)

                         \(x=\frac{6}{5}\)

=a + (1/2x2/5+4/5+1)

=a+2 =136

       a =136-2

       a =134

a) \(\dfrac{4}{5}< \dfrac{5}{a}< \dfrac{10}{7}\) \(\left(a\inℤ\right)\)

\(\Leftrightarrow\dfrac{7}{10}< \dfrac{a}{5}< \dfrac{5}{4}\)

\(\Leftrightarrow\dfrac{7.5}{10}< a< \dfrac{5}{4}.5\)

\(\Leftrightarrow\dfrac{7}{2}< a< \dfrac{25}{4}\)

\(\Leftrightarrow a\in\left\{4;5;6\right\}\)

b) \(\dfrac{2}{5}< \dfrac{a-1}{10}< \dfrac{8}{15}\)

\(\Leftrightarrow\dfrac{2.10}{5}< a-1< \dfrac{8.10}{15}\)

\(\Leftrightarrow4< a-1< \dfrac{16}{3}\)

\(\Leftrightarrow5< a< \dfrac{19}{3}\)

\(\Leftrightarrow a\in\left\{6\right\}\)

c) \(\dfrac{12}{7}< \dfrac{4}{a}< \dfrac{8}{3}\)

\(\Leftrightarrow\dfrac{3}{8}< \dfrac{a}{4}< \dfrac{7}{12}\)

\(\Leftrightarrow\dfrac{3.4}{8}< a< \dfrac{7.4}{12}\)

\(\Leftrightarrow\dfrac{3}{2}< a< \dfrac{7}{3}\)

\(\Leftrightarrow a\in\left\{2\right\}\)

d) \(5< a^2-15< 16\)

\(\Leftrightarrow10< a^2< 31\)

\(\Leftrightarrow\sqrt[]{10}< a< \sqrt[]{31}\)

\(\Leftrightarrow a\in\left\{4;5\right\}\)

Bài 1: 

a) =25,97+(6,54+103,46)

=25,97+110

=135,97

b)136x75+75x64

=75x(136+64)

=75x200

=15 000

c) (21/8+1/2):5/16

=(21/8+4/8)x16/5

=25/8x16/5

=10

d)3/17-4/5+14/17

=(3/17+14/17)-4/5

=1-4/5

=1/5

Bài 2:

a)720:\([41-(2x-5)]\)=120

              41 - (2x-5)                 =720:120

              41 - (2x-5)                 =6

                      2x-5                   =41-6

                      2x-5                   =35

                      2x                      =35+5

                      2x                      =40

                      x                        =40:2

                      x                        =20

b)2/3 x X +3/4=3

   2/3 x X        =3-3/4

   2/3 x X        =12/4-3/4

   2/3 x X        =9/4

             x        =9/4:2/3

             x        =9/4x3/2

             x        =27/8

c) x+0,34=1,19x1,02

    x+0,34=1,2138

    x         =1,2138-0,34

    x         =0,8738