\(\Rightarrow28\left(x-9\right)=20.35\Rightarrow28x-252=700\Rightarrow28x=952\Rightarrow x=34\)
\(\frac{x-9}{35}=\frac{20}{28}=\frac{5}{7}=\frac{25}{35}\)
=>x-9=25
=>x=25+9
=>x=34
vậy x=34
x-9/35=20/28
28x(x-9)/980=700/980
28xX-28x9=700
28xX-252=700
28xX=700+252
28xX=952
x=952/28
x=34