^0^0^

\(\frac{145,7-290:5+0,3}{x:8+13}=4\)

=> \(\frac{145,7-58+0,3}{x:8+13}=4\)

=> \(\frac{88}{x:8+13}=4\)

=> \(x:8+13=88:4\)

=> \(x:8+13=22\)

=> x : 8 = 9

=> x = 9 x 8 = 72

Vậy x = 72

\(x = {-b \pm \s\)

= \(\frac{145,7-58+0,3}{X:8+13}=4\)

=\(\frac{87,7+0,3}{X:8+13}=4\)

= \(\frac{90}{X:8+13}=4\)

X : 8 + 13 = 90 : 4

X : 8 + 13 = 22,5

X : 8 = 22,5 - 13

X : 8 = 9,5

X = 9,5 x 8 

X = 76

\(\frac{145,7-290\div5+0,3}{x\div8+13}=4\)

\(\frac{88}{x\div8+13}=4\)

\(x\div8+13=88\div4\)

\(x\div8+13=22\)

\(x\div8=22-13\)

\(x\div8=9\)

\(x=9\times8\)

\(x=72\)

\(\frac{88}{y:8+13}\)=\(\frac{88}{y:8}+\frac{88}{13}\)=
vô lý 
ko có điều kiện của y

@@ quên

145,7 - 280: 5 + 0,3:y:8 + 13 = 4

145,7 - 56 + 0,3:y:8 + 13  = 4

(145,7 - 56 + 13) + 0,3:y:8 = 4

102,7 + 0,3:y:8 = 4

              0,3:y:8 = 4 -  102,7 

              0,3:y: 8 = - 98,7

              0,3: y = -  98,7 x 8

               0,3 : y =- 789,6

                        y = 0,3 : (-789,6)

                          y = - \(\dfrac{1}{2632}\)

=> 145,7-56+0,3/ y:8+13=4

=>89,7+0,3/y:8+13=4

=>90/y:8+13=4

=>y:8+13=90:4

=>y:8+13=22,5

=>y:8=22,5-13

=>y:8=9,5

=>y=9,5x8

=>76

(x : 8 + 13 ) . 4 = 146 + 290 : 5  

( x : 8 + 13 ) . 4 = 146 + 58

( x : 8 + 13 ) . 4 = 204

x : 8 + 13 = 204 : 4

x : 8 + 13 = 51

x : 8 = 51 - 13

x : 8 = 38

x = 38 x 8 

x = 304

(x : 8 + 13) . 4 = 146 + 290 : 5

(x : 8 + 13) . 4 = 146 + 58

(x : 8 + 13) . 4 = 204

x : 8 + 13 = 51

x : 8 = 38

x = 304

245,7 - 58+ 0,3= 4 x ( x:4 + 2,7)

188= 4x( x:4 + 2,7)

4x ( x:4 + 2,7)= 188

(x:4 + 2,7) = 188 :4

(x:4 +2,7)= 47

(x:4)       = 47 - 2,7

(x:4)       =44,3

x            = 44,3 x 4

x= 177,2

245,7-290:5+9,3=4.(x:4+2,7)

=>4.(x:4+2,7)=245,7-58+0,3=188

=>x:4+2,7=188:4=47

=>x:4=47-2,7=44,3

=>x=44,3x4

=>x=177,2

=> 245,7-58+1,3=4.(\(\frac{X}{4}+2,7\))

<=> 188=\(\frac{4X}{4}+10,8\)

<=> 188=X+10,8

X=188-10,8 =177,2

nhớ chọn D/án mk nha