\(a,25\%x=42,6-3,28\\ \Leftrightarrow\dfrac{1}{4}x=39,32\\ \Leftrightarrow x=157,28\)

\(b,x:40\%=7,25+6,75\\ \Leftrightarrow x:40\%=14\\ \Leftrightarrow x=5,6\)

\(c,\dfrac{7011}{25}:\left(x-42,6\right)=117,14-47,03\\ \Leftrightarrow\dfrac{7011}{25}:\left(x-42,6\right)=70,11\\ \Leftrightarrow x-42,6=4\\ \Leftrightarrow x=46,6\)

\(d,0,3\left(x+\dfrac{1}{3}\right)=\dfrac{1}{2}\cdot\left(0,81:27\right)\\ \Leftrightarrow0,3\left(x+\dfrac{1}{3}\right)=0,015\\ \Leftrightarrow x+\dfrac{1}{3}=0,05\\ \Leftrightarrow x=-\dfrac{17}{60}\)

a) 1/4 x X = 39,32

X = 39,32 : 1/4

X = 157,28

a)x=157,28                      c)x=179/7

b)x=5,6.                            d)x=1/192

\(\left(25\%\cdot x-7,25\right)+4,25=10\)

=>\(x\cdot0,25-3=10\)

=>\(x\cdot0,25=13\)

=>\(x=\dfrac{13}{0,25}=52\)

\(\dfrac{7011}{25}:\left(x-42.6\right).15=13\)

\(\Rightarrow\dfrac{7011}{\dfrac{25}{\left(x-42,6\right)}}.0,15=13\)

\(\Rightarrow\dfrac{280,44}{\left(x-42,6\right)}.0,15=13\)

\(x-\left(280,44-42,6\right)\)

\(x=237.8+86,7\)

\(x=324,54\)

\(\)Vậy x=324,54

b.

\(7,2-\left(x+3,75:2,1\right):1,9=5,2\)

\(\Rightarrow7,2+\dfrac{-\left(x-\dfrac{3,75}{2,1}\right)}{1,9}=5,2\)

\(7,2+\dfrac{-\left(x-1,8\right)}{1,9}=5,2\)

a , x = 10

b, x= 19.585

c.x=3.04

d,x=100

chúc bạn học giỏi !

a, x* 7,25 = 72,50

    x         = 72,50 : 7,25

    x         =   10

b, 470,04 : x = 24

                 x  = 470,04 : 24

                  x = 19,585

c, 32,68 *x = 99,3472

              x = 99,3472 : 32,68

              x = 3,04

d, 625,17 : x = 6,2517

                 x = 625,17 : 6,2517

                  x = 100

\(a,\frac{7011}{25}:\left(x-42,6\right)=117,14-47,03\)

\(=\frac{7011}{25}:\left(x-42,6\right)=70,11\)

\(\Rightarrow\left(x-42,6\right)=\frac{7011}{25}:70,11\)

\(\Rightarrow x=4+42,6\)

\(\Rightarrow x=46,6\)

b ko co bai b a

Phần a thì có bạn giải rồi nên mình sẽ giải phần b :

0,3 x ( X+ (1)/(3) ) =(1)/(2) x (0,81 : 2,7)

a) 7,25×6,93+7,25×2,07+7,25×1

=7,25×(6,93+2,07+1)

=7,25×10

=72,5

b) 24,8:0,5+24,8×8

=24,8×2+24,8×8

=24,8×(2+8)

=24,8×10

=248

Áp dụng tính chất của dãy tỷ số bằng nhau

\(\frac{3x-1}{40-5x}=\frac{25-3x}{4x-34}=\frac{\left(3x-1\right)+\left(25x-3x\right)}{\left(40-5x\right)+\left(5x-34\right)}=4\)

\(\Rightarrow\frac{3x-1}{40-5x}=4\)

\(\Rightarrow3x-1=3\left(40-5x\right)\)

\(\Rightarrow3x-1=160-20x\)

\(\Rightarrow23x=161\)

\(\Rightarrow x=161:23\)

\(\Rightarrow x=7\)