a)\(\frac{5}{9}\times x-1=\frac{8}{9}\)

\(\frac{5}{9}\times x=\frac{8}{9}+1\)

\(\frac{5}{9}\times x=\frac{17}{9}\)

\(x=\frac{17}{9}:\frac{5}{9}\)

\(x=\frac{17}{5}\)

b)\(x+x\times\frac{1}{3}:\frac{2}{9}+x:\frac{2}{7}=252\)

\(x+x\times\frac{3}{2}+x:\frac{2}{7}=252\)

\(x.1+x.\frac{3}{2}+x.\frac{7}{2}=252\)

\(x\left(1+\frac{3}{2}+\frac{7}{2}\right)=252\)

\(x\times6=252\)

\(x=252:6\)

\(x=42\)

a,5/9.x-1=8/9

5/9.x=17/9

x=17/5

b,x+x.1/3:2/9+x:2/7=252

x+x.1/3.9/2+x.7/2=252

x(1+1/3.9/2+7/2)=252

x.6=252

x=42

\(x+x\times\frac{1}{4}\div\frac{2}{7}+x\div\frac{2}{9}=255\)

\(\Rightarrow x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)

\(\Rightarrow x+x\times\frac{7}{8}+x\times\frac{9}{2}=255\)

\(\Rightarrow x.\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)

\(\Rightarrow x\cdot\frac{51}{8}=255\)

\(\Rightarrow x=255\div\frac{51}{8}\)

\(\Rightarrow x=255\times\frac{8}{51}\)

\(\Rightarrow x=40\)

Vậy x = 40 

a)\(x+\dfrac{2}{3}x\dfrac{5}{6}=7\)

\(x+\dfrac{10}{18}=7\)

\(x=7-\dfrac{10}{18}\)

\(x=\dfrac{58}{9}\)

b)\(9-xx\dfrac{1}{2}=\dfrac{3}{4}\)

\(xx\dfrac{1}{2}=9-\dfrac{3}{4}\)

\(xx\dfrac{1}{2}=\dfrac{33}{4}\)

\(x=\dfrac{33}{4}:\dfrac{1}{2}\)

\(x=\dfrac{33}{2}\)

c)\(18-x:\dfrac{2}{3}=\dfrac{4}{5}-\dfrac{1}{10}\)

\(18-x:\dfrac{2}{3}=\dfrac{7}{10}\)

\(x:\dfrac{2}{3}=18-\dfrac{7}{10}\)

\(x:\dfrac{2}{3}=\dfrac{173}{10}\)

\(x=\dfrac{173}{10}x\dfrac{2}{3}\)

\(x=\dfrac{173}{15}\)

y+y x 1/3 : 2/9 + y :2/7 = 252

y x 1 + y x (1/3 x 9/2 ) + y x 7/2 = 252

y x 1/1 + y x 3/2 + y x 7/2 = 252

y x (1/1 + 3/2 + 7/2 ) = 252

y x 6 = 252

y = 252 : 6

y = 42

\(x+x×\frac{1}{3}:\frac{2}{9}+x×\frac{2}{7}=252\)

\(\Rightarrow x+x×\frac{1}{3}×\frac{9}{2}+x×\frac{7}{2}=252\)

\(x\left(1+\frac{1}{3}×\frac{9}{2}+\frac{7}{2}\right)=252\)

\(x×\frac{36}{6}=252\)

\(x×6=252\)

\(x=252:6\)

\(x=43\)

x+x.1/3:2/9+x:2/7=252

x+x.1/3.9/2+x.7/2=252

x(1+1/3+9/2+7/2)=252

x.36/6                 =252

=>x                     =252:6

=>x                     =42

Sửa 42→43 cho chị nha

Thiên thần nhỏ đừng coppy bài người khác nữa

y + y x1/3 : 2/9 + y : 2/7 = 252

y x 1 + y x ( 1/3 x 9/2 ) + y x 7/2 =252

y x1/1 + y x 3/2 + y x 7/2 =252

y x ( 1/1 + 3/2 + 7/2 ) =252

y x ( 2/2 + 3/2 + 7/2 ) =252

y x           6              = 252

y                               = 252 : 6

y                            =  42

Đáp số là???? ¿¿??????? ¿? ¿??????????? ¿

Là42

y + y x 1/3 : 2/9 + y : 2/7 = 252

y x 1 + y x 3/2 + y x 7/2   = 252

y x ( 1 + 3/2 + 7/2 )          = 252

y x          6                        = 252

                                  y     = 252 : 6

                                  y     = 42

Chúc bạn học giỏi.

1+1+1+1+1+1+2+5+10+4+7=34

(1+9)+(2+8)+(3+7)+(4+6)+(5+5)+(10+0)

=10+10+10+10+10+10

=10x6

=60

Xx1+3=7

X+3=7x1

X+3=7

     X=7-3

     X=4