0,3 + 14/15 : y = 8/15

14/15 : y = 8/15 - 0,3

14/15 : y = 7/30

           y  = 14/15 : 7/30

           y  = 4

145,7 - 280: 5 + 0,3:y:8 + 13 = 4

145,7 - 56 + 0,3:y:8 + 13  = 4

(145,7 - 56 + 13) + 0,3:y:8 = 4

102,7 + 0,3:y:8 = 4

              0,3:y:8 = 4 -  102,7 

              0,3:y: 8 = - 98,7

              0,3: y = -  98,7 x 8

               0,3 : y =- 789,6

                        y = 0,3 : (-789,6)

                          y = - \(\dfrac{1}{2632}\)

=> 145,7-56+0,3/ y:8+13=4

=>89,7+0,3/y:8+13=4

=>90/y:8+13=4

=>y:8+13=90:4

=>y:8+13=22,5

=>y:8=22,5-13

=>y:8=9,5

=>y=9,5x8

=>76

 4/5x 0,5+12/15 x 0,3 + 8:10 x 0,2

4/5x0,5+4/5x0,3+4/5x0,2

4/5x(0,5+0,3+0,2)

4/5x1=4/5

BAn k nha!

Bằng \(\frac{4}{5}\)

Và 0,8 nha bạn

Chúc các bạn học giỏi

\(x\cdot0,3+x\cdot0,1+x\cdot0,6+x=8\)

=>\(x\left(0,3+0,1+0,6+1\right)=8\)

=>2x=8

=>x=8/2=4

\(x\times0,3+x\times0,1+x\times0,6+x=8\\x\times(0,3+0,1+0,6+1)=8\\x\times(0,4+0,6+1)=8\\x\times(1+1)=8\\x\times2=8\\x=8:2\\x=4\)

a) \({( - 2)^4} \cdot {( - 2)^5} = {\left( { - 2} \right)^{4 + 5}} = {\left( { - 2} \right)^9}\)

 \({( - 2)^{12}}:{( - 2)^3} = {\left( { - 2} \right)^{12 - 3}} = {\left( { - 2} \right)^9}\)

Vậy \({( - 2)^4} \cdot {( - 2)^5}\) = \({( - 2)^{12}}:{( - 2)^3}\);

b) \({\left( {\frac{1}{2}} \right)^2} \cdot {\left( {\frac{1}{2}} \right)^6} = {\left( {\frac{1}{2}} \right)^{2 + 6}} = {\left( {\frac{1}{2}} \right)^8}\)

\({\left[ {{{\left( {\frac{1}{2}} \right)}^4}} \right]^2} = {\left( {\frac{1}{2}} \right)^{4.2}} = {\left( {\frac{1}{2}} \right)^8}\)

Vậy \({\left( {\frac{1}{2}} \right)^2} \cdot {\left( {\frac{1}{2}} \right)^6}\) = \({\left[ {{{\left( {\frac{1}{2}} \right)}^4}} \right]^2}\)

c) \({(0,3)^8}:{(0,3)^2} = {\left( {0,3} \right)^{8 - 2}} = {\left( {0,3} \right)^6}\)

\({\left[ {{{(0,3)}^2}} \right]^3} = {\left( {0,3} \right)^{2.3}} = {\left( {0,3} \right)^6}\)

Vậy \({(0,3)^8}:{(0,3)^2}\)= \({\left[ {{{(0,3)}^2}} \right]^3}\).

d) \({\left( { - \frac{3}{2}} \right)^5}:{\left( { - \frac{3}{2}} \right)^3} = {\left( { - \frac{3}{2}} \right)^{5 - 3}} = {\left( { - \frac{3}{2}} \right)^2} = {\left( {\frac{3}{2}} \right)^2}\)

Vậy \({\left( { - \frac{3}{2}} \right)^5}:{\left( { - \frac{3}{2}} \right)^3}\) = \({\left( {\frac{3}{2}} \right)^2}\).

y=8

HT

^0^0^

=10+(0,1+0,9)+(0,2+0,8)+(0,3+0,7)+(0,6+0,4)+(0,5+0,5)

=10+1+1+1+1+1

=15

ban k minh nha 

carm on ban nhieu

b ) x : 8 = x x 8 - 56,78 = 69,11 x 2

x : 8 = x x 8 - 56,78 = 138,22

x : 8 = x x 8 = 138,22 + 56,78 = 195

= > x = 

Ta có: \(\frac{33}{8}:0,2=X:0,3\)

=>\(X:\frac{3}{10}=\frac{33}{8}:\frac15=\frac{33}{8}\cdot5=\frac{165}{8}\)

=>\(X=\frac{165}{8}\cdot\frac{3}{10}=\frac{165}{10}\cdot\frac38=\frac{33}{2}\cdot\frac38=\frac{99}{16}\)

\(\frac{33}{8}:\frac{1}{5}=x:\frac{3}{10}\)

\(\Rightarrow\frac{165}{8}=x:\frac{3}{10}\)

\(\Rightarrow x=\frac{99}{16}\)

study well 

33/8:0,2=x:0,3

33/8:1/5=x:3/10

33/8.5=x:3/10

165/8=x:3/10

165/8.3/10=x

=>x=99/80

Vậy x=99/80

   Hok tốt