-47*69+31*(-47)=-47*(69+31)=-47*100=-4700

a) ( 735 - 135 ) + ( 243 - 143 ) = 600 + 100 

= 700

b) 31 x ( 118 - 48 ) = 31 x 70 

= 2170

c) ( 25 x 32 ) x7 = 800 x 7

= 2400

d ) 47 x ( 63 + 47 ) - 38

= 47 x 100 - 38

= 4700 - 38 

=4662

h ) ( 53 + 47 ) x ( 39 + 21 ) = 100 x 60 

= 6000

a: =25x100-150=2500-150=2350

c: \(=520:\left\{515\cdot25\right\}\)

=104/2575

\(47\cdot69-31\cdot(-47)\\=47\cdot69-31\cdot(-1)\cdot47\\=47\cdot69+31\cdot47\\=47\cdot(69+31)\\=47\cdot100\\=4700\)

\(=47.69-31.47.\left(-1\right)\\ =47.\left(69+31\right)\\ =47.100=4700\)

a) \(136+326+64\)

\(=\left(136+64\right)+326\)

\(=200+326\)

\(=526\)

b) \(69+\left(31+57\right)\)

\(=\left(69+31\right)+57\)

\(=100+57\)

\(=157\)

c) \(755+321+145+179\)

\(=\left(755+145\right)+\left(321+179\right)\)

\(=900+500\)

\(=1400\)

d) \(17+123+378+583+122\)

\(=\left(17+583\right)+\left(378+122\right)+123\)

\(=600+500+123\)

\(=1100+123\)

\(=1223\)

\(50.\left(21+79\right)+17.\left(31+69\right)\)

\(\Rightarrow50.100+17.100\)

\(\Rightarrow100.\left(50+17\right)\)

\(=100.67=6700\)

50. (21+79) + 17. (31+69)

= 50.100 + 17. 100

= 100. (50+17)

= 100.67 

= 6700

b, 53.39 + 47.39 - 53.21 - 47.21
  = 39( 53 + 47) - 21  53 + 47)
  = 39.100 - 21.100
  = 100(39 - 21) 
   = 100. 18
   = 1800  

bấm cho mình đúng nha ^_^

a)=78.(31+24+17)+22.72

=72.(78+22)

=72.100

=7200

b)=39.(53+47)-21.(53+47)

=100.(39-21)

=100.18

=1800

a) (26-6)*(-4)+31*(-7-13)

=-80+-620

=-700

hacker 2k6