\(x+x:5\cdot7\cdot5+x:2\cdot9=315\)

\(x+7x+4.5x=315\)

\(x\left(1+7+4.5\right)=315\)

\(x\cdot12.5=315\)

\(x=315:12.5\)

\(x=25.2\)

a, \(\frac{x}{13}=\frac{35}{91}\)

\(\frac{x}{13}=\frac{5}{13}\rightarrow x=5\)

b, Cậu xem lại đb xem có nhầm ko

Nếu đb là \(9+x=13-x\)

\(\rightarrow2x=4\rightarrow x=2\)

c, Cậu cx xem lại đb ik

a, \(\frac{x}{13}=\frac{35}{91}\)
=> x = 35.13 : 91 
=> x = 5 
b ) \(\frac{x}{13}-x=\frac{5}{6}-9=\frac{-49}{6}\)
=> \(\frac{x-13x}{13}=\frac{-49}{6}\)
=> -12x . 6 = -49 . 13 
=> -12x . 6 = - 637 
=> -12x = -637 : 6 =\(\frac{-637}{6}\)
=> x = \(\frac{-637}{6}:-12=\frac{-637}{72}\)
c, \(x+\frac{x}{5}.7,5+\frac{x}{2}.9=315\)
\(x+\frac{7,5x}{5}+\frac{9x}{2}=315\)
\(x+\frac{60x}{10}=315\)
\(x+6x=315\)
\(7x=315\Rightarrow x=315:7=45\)
d, \(\frac{2}{3}.x+\frac{1}{2}=\frac{9}{10}-\frac{1}{5}\)
\(\frac{2}{3}x+\frac{1}{2}=\frac{7}{10}\)
\(\frac{2}{3}x=\frac{7}{10}-\frac{1}{2}=\frac{1}{5}\)
\(x=\frac{1}{5}:\frac{2}{3}=\frac{3}{10}\)

mình mới đọc câu a thôi nhé

x=5

a)x=5 nha ban