3.95=285 nha 

= 285 nha

3,95 = 285

\(9,5x+2,5\left(1-x\right)=3,95\)

\(\Leftrightarrow9,5x+2,5-2,5x=3,95\)

\(\Leftrightarrow7x=1,45\)

\(\Leftrightarrow x=\dfrac{29}{140}\)

9,5.x+2,5.(1-x)=3,95` 

`⇒` `(14x+5)/2` `=` `79/20`

`⇒` `((14x+5).20)/20` `=` `(2.79)/20`

`⇒` `(4x+5).20=2.79`

`⇒` `14x+5=79/10`

`⇒` `14x=29/10`

`⇒` `x` `=` `29/140` `≈` `0,2071`

50 x 7 x 2

= (50 x 2) x 7

= 100 x 7

= 700

(50 x 2)x7                                                                                                                                                                                                            = 100 x 7                                                                                                                                                                                                                  = 700            

cảm ơn mấy bạn nha

=1/10+2/10+3/10+4/10+5/10+6/10

=21/10

[-1/7]=-1

[3,7]=3

[-4]=-4

[-43/10]=[-4,3]=-5

1,

a, \(x\)x 124= 4829-365

 \(x\)x 124 = 4464

\(x\)= 4464 :124

\(x\)= 36.

b,\(x\)x 137 = 25 x 3 

   \(x\)x 137 = 75

\(x\)= \(\frac{75}{137}\)

2,

\(\frac{4}{5}\)x\(\frac{3}{7}+\frac{4}{5}\)x\(\frac{6}{7}-\frac{4}{5}\)x\(\frac{4}{10}\)

=\(\frac{4}{5}\)x\(\left(\frac{3}{7}+\frac{6}{7}-\frac{4}{10}\right)\)=\(\frac{4}{5}\)x\(\frac{31}{35}\)\(\frac{124}{175}\)

\(\text{Bài }1\text{ : Tìm }x\text{ : }\)

\(a,\text{ }x\text{ x }124=4829-365\)

     \(x\text{ x }124=4464\)

     \(x=4464\text{ : }124\)

     \(x=36\)

\(b,\text{ }x\text{ x }137=25\text{ x }3\)

     \(x\text{ x }137=75\)

     \(x=75\text{ : }137\)

     \(x=\frac{75}{137}\)

\(\text{Bài }2\text{ : Tính bằng cách thuận tiện nhất : }\)

      \(\frac{4}{5}\text{ x }\frac{3}{7}+\frac{4}{5}\text{ x }\frac{6}{7}-\frac{4}{5}\text{ x }\frac{4}{10}\)

\(=\frac{4}{5}\text{ x }\left(\frac{3}{7}+\frac{6}{7}-\frac{4}{10}\right)\)

\(=\frac{4}{5}\text{ x }\left(\frac{9}{7}-\frac{4}{10}\right)\)

\(=\frac{4}{5}\text{ x }\frac{31}{35}\)

\(=\frac{124}{175}\)

mẹ ơi dễ thế để con giải cho:

Bài 1:

a. X x 124=4829-365

    X x 124         =4464

    X                  = 4464:124

    X                 =36

b tương tự như câu a

Bài 2:

\(\frac{4}{5}\)x \(\frac{3}{7}\)+\(\frac{4}{5}\)x \(\frac{6}{7}\)-\(\frac{4}{5}\)x \(\frac{4}{10}\)

=\(\frac{4}{5}\)x(\(\frac{6}{7}\)+ \(\frac{3}{7}\)-\(\frac{4}{10}\))

= \(\frac{4}{5}\)x \(\frac{31}{35}\)

\(\frac{124}{175}\)

1. \(450\%+3=\dfrac{9}{2}+3=\dfrac{15}{2}\)

2. \(\dfrac{1}{4}-2,75+2=0,25-2,75+2=-0,5\)

3. \(\dfrac{3}{10}+2,7=0,3+2,7=3\)