\(a\frac{4}{20}=\frac{1}{5}\)
b) 8,75 x \(x\) + 1,25 x \(x\) = 20
( 8,75 + 1,25 ) x \(x\) = 20
10 x \(x\) = 20
\(x=\) 20 : 10
\(x\) = 2
a,Ta có \(\frac{4}{x}=\frac{1}{5}\Rightarrow x\times1=4\times5\Rightarrow x=20\)
Vậy x=20
b, ta có \(8,75\times x+1,25\times x=20\)
\(\Rightarrow x\times\left(8,75+1,25\right)=20\)
\(\Rightarrow x\times10=20\)
\(\Rightarrow x=\frac{20}{10}=2\)
Vậy x=2