=789+680+11+(-789)

=789+(-789)+680+11

=680+11

=691

x + 254 = 680

x = 680 - 254

x = 426

x = 426

\(a,2\times31\times12+4\times6\times42+8\times27\times3\)

\(=24\times31+24\times42+24\times27\)

\(=24\times\left(31+42+27\right)\)

\(=24\times100\)

\(=2400\)

\(b,583.931+69.\left(170+583\right)+31.170\)

\(=583.931+69.170+69.583+31.170\)

\(=583.\left(931+69\right)+170.\left(69+31\right)\)

\(=583.1000+170.100\)

\(=583000+17000\)

\(=600000\)

\(c,732.976+24.\left(680+732\right)+76.680\)

\(=732.976+24.680+24.732+76.680\)

\(=732.\left(976+24\right)+680.\left(24+76\right)\)

\(=732.1000+680.100\)

\(=732000+68000\)

\(=800000\)

Học tốt

a)2400

b)600000

c)800000

a) 2 x 31 x 12 + 4 x 6 x 42 + 8 x 27 x 3

= 24 x 31 + 24 x 42 + 24 x 27

= 24 x ( 31 + 42 + 27 )

= 24 x 100

= 2400

b) 583 x 931 + 69 x ( 170 + 583 ) + 31 x 170

= 583 x 931 + 69 x 170 + 69 x 583 + 31 x 170

= 583 x ( 931 + 69 ) + 170 x ( 69 + 31 )

= 583 x 1000 + 170 x 100

= 583000 + 17000

= 600000

c) 732 x 976 + 24 x ( 680 + 732 ) + 76 x 680

= 732 x 976 + 24 x 680 + 24 x 732 + 76 x 680

= 732 x ( 976 + 24 ) + 680 x ( 24 + 76 )

= 732 x 1000 + 680 x 100

= 732000 + 68000

= 800000

6800 : 10 = 680 

x=680x10

x=6800

x : 10 = 680

      x = 680 x 10 

       x = 6800

Ta có: 612=2².3².17 ; 680= 5.17.2³

Ta có: ƯCLN(612;680)= 2².17=68

Vậy: \(x\inƯ\left(68\right),x\ge35\Rightarrow x=68\)

60%x + 2/3x +x=680

x(3/5+2/3+1)=680

Đến bước này bạn làm được chưa?

60%x+2/3x+x=680

=> 0,6x+2/3x+x=680

=> x.(0,6+2/3+1)=680

=> x.34/15         =680

=> x                  =680:34/15

=> x                  =300

k mik nhé  Vuthimailoan

\(60\%x+\frac{2}{3}x+x=680\)

\(\frac{3}{5}x+\frac{2}{3}x+x=680\)

\(x\left(\frac{3}{5}+\frac{2}{3}+1\right)=680\)

\(\frac{34}{15}x=680\)

\(x=300\)

Vậy x = 300

a) x - 306 = 504

x = 504 + 306

x = 810

b) x + 254 = 680

x = 680 - 254

x = 426

17 x \(x\) + 15 x  \(x\) x 3 + 12 x 15 - \(x\) x 4 = 680

\(x\) x ( 17 + 15 x 3 - 4) + 180 =680

\(x\) x ( 17 + 45 - 4) = 680 - 180

\(x\) x 58 = 500

\(x\) = 500/58

\(x\) = 250/29