a,64 x 25 + 35 x 25 +25=25.(64+35+1)=25.100=2500

b) 58 x 42 + 32 x 8 + 5=2436+256+5=2697

c) A =1 +2+3+4+...+100=(100+1)x[(100-1):1+1]:2=5050

\(64\times25+35\times25+25\)

\(=25\times\left(64+35+1\right)\)

\(=25\times100\)

\(=2500\)

(190 - 2 x X) : 35 + 32 = 16

(190 - 2x) : 35 = 16 - 32

(190 - 2x) : 35 = -16

190 - 2x = -16 x 35

190 - 2x = -560

-2x = -560 - 190

-2x = -750

\(x=\frac{-750}{-2}=375\)

abc + a,bc + ab,c = 666

​abc = 600

100a + 10b + c + a + 0,(10b+c )+ (10a+ b) + 0,0c = 666

111a + 11,10b + 2,0c = 666

 ........??????????????????????????

a) x + 3,5 = 4,72 + 2,28

    x + 3,5 =       7

    x          = 7 - 3,5

    x          =  3,5

b) 5,6 : x = 4

           x = 5,6 : 4 

           x =    1,4

ủng hộ nha  fan khởi my

Nhanh giúp mk vs

Vì A chia 65 dư 22 

=> A =\(65x+22\)

khi đó \(\frac{A}{13}=\frac{65x+22}{13}=5x+\frac{22}{13}\)

=> khi đó A:13 dư 9

nhanh nha

Ta có: \(5.\frac{a}{b}=\frac{a+b}{b}=\frac{a}{b}+\frac{b}{b}=\frac{a}{b}+1\)

<=> \(5.\frac{a}{b}-\frac{a}{b}=1\)

<=> \(4.\frac{a}{b}=1\) => \(\frac{a}{b}=\frac{1}{4}\)

Đáp số: \(\frac{a}{b}=\frac{1}{4}\)

Dấu \(.\)là dấu nhân

Ta có :

\(\frac{a}{b}.5=\frac{a+b}{b}\)

\(\Rightarrow\frac{a.5}{b}=\frac{a+b}{b}\)

\(\Rightarrow a.5=a+b\)

\(\Rightarrow a.5-a=b\)

\(\Rightarrow a.\left(5-1\right)=b\)

\(\Rightarrow a.4=b\)

Nên : 

\(\frac{a}{b}=\frac{a}{a.4}=\frac{1}{4}\)

Vậy  \(\frac{a}{b}=\frac{1}{4}\)

462 : X = 38,5

           X= 462:38,5

           X=12

X x32 = 2208

X         =2208:32

X          =69

159 - x = 72

          x  =159 - 72

           x  =87

X1 = 12

X2 = 69

X3 = 87