\(a,86-\left(86+x\right)=10\\ \Rightarrow86+x=76\\ \Rightarrow x=10\\ b,10-x=7-\left(-8\right)\\ \Rightarrow10-x=15\\ \Rightarrow x=-5\\ c,\left(-24+x\right)-43=15\\ \Rightarrow x-24=58\\ \Rightarrow x=82\)

86 x 102 x ( 86-43 x 2)

= 86 x 102 x (86-86)

= 86 x 102 x 0

= 0

86 x102 x(86 -43 x2)

=86x102x86-86x102x43x2

=86x102x86-86x102x86

=0

43  × ( x - 19 ) = 86

x - 19 = 86 : 43

x - 19 = 2

x= 2 + 19

x = 21

43 x ( x - 19 ) = 86

        ( x - 19 ) = 86 : 43

          x - 19   = 2

          x          = 2 + 19

          x          = 21

43 x ( x - 19 ) = 86

         x - 19   = 86 : 43

         x - 19   = 2

         x          = 2 + 19

         x          = 21

43 × 11 = 473     86 × 11 = 946     73 × 11 = 803

43.(x-19)=86

x-19=2

x=21

\(43\times\left(x-19\right)=86\)

\(x-19=86\div43\)

\(x-19=2\)

\(x=2+19\)

\(x=21\)

@#$%^&* !

\(43\times\left(x-19\right)=83\)

\(\Rightarrow x-19=86:43\)

\(\Rightarrow x-19=2\)

\(\Rightarrow x=2+19\)

\(\Rightarrow x=21\)

Vậy x = 21

_Chúc bạn học tốt_

86:9= 9 (dư 5) 

65:7=  9 (dư 2)

43:5= 8 (dư 3)

86:7= 12 (dư 2)

65:5= 13 

43:3=14 (dư 1)

76:7= 10(dư 6)

87:6= 14 (dư 3)

65:5= 13 

86/9=9(dư 5)

65/7=9(dư 2)

43/5=8(dư 3)

86/7=12(dư 2)

65/5=13

43/3=12(dư 1)

76/7=10(dư 6)

87/6=14(dư 3)

65/5=13

không thể giải thích được

96x( 43 + 48 )x(86–20)=96x91x66

=576576

\(\dfrac{2}{5}+\dfrac{4}{5}:4=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{3}{5}\)

\(\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}=\dfrac{3}{8}\left(\dfrac{7}{4}-1\right)=\dfrac{3}{8}\times\dfrac{3}{4}=\dfrac{9}{32}\)

\(\dfrac{6}{5}-3:\dfrac{15}{4}=\dfrac{6}{5}-\dfrac{4}{5}=\dfrac{2}{5}\)

\(=\dfrac{2}{5}+\dfrac{4}{5}\times\dfrac{1}{4}\\ =\dfrac{2}{5}+\dfrac{1}{5}\\ =\dfrac{3}{5}\\ \\ =\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}\times1\\ =\dfrac{3}{8}\times\left(\dfrac{7}{4}-1\right)\\ =\dfrac{3}{8}\times\dfrac{3}{4}\\ =\dfrac{9}{32}\\\\ =\dfrac{6}{5}-3\times\dfrac{4}{15}\\ =\dfrac{6}{5}-\dfrac{4}{5}\\ =\dfrac{2}{5}\)

\(\dfrac{2}{5}+\dfrac{4}{5}:4=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{3}{5}\\ \dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}=\dfrac{3}{8}\times\dfrac{7}{4}-\dfrac{3}{8}\times1=\dfrac{3}{8}\times\left(\dfrac{7}{4}-1\right)=\dfrac{3}{8}\times\dfrac{3}{4}=\dfrac{9}{32}\\ \dfrac{6}{5}-3:\dfrac{15}{4}=\dfrac{6}{5}-\dfrac{4}{5}=\dfrac{2}{5}\)