Ta có :
\(\frac{5,7}{3,5}=-\frac{x}{0,45}\)
\(\Rightarrow x=\frac{5,7}{3,5}.\left(-0,45\right)\)
\(\Rightarrow x=-\frac{513}{700}\)
Vậy x = - 513 / 700
\(5,7:0,35=\left(-x\right):0,45\)
\(\Leftrightarrow-x=\frac{5,7\cdot0,45}{0,25}=10.26\)
\(\Leftrightarrow x=-10,26\)