Question

 a, x/4 = -3/5

 b, 2,1/0,7 = x/3

Answer 1

a) \(\dfrac{x}{4}=\dfrac{-3}{5}\)

\(\Rightarrow x=\dfrac{4\cdot-3}{5}\)

\(\Rightarrow x=-\dfrac{12}{5}\) 

b) \(\dfrac{2,1}{0,7}=\dfrac{x}{3}\)

\(\Rightarrow x=\dfrac{2,1\cdot3}{0,7}\)

\(\Rightarrow x=9\)

Answer 2

Lời giải:
a. $x=\frac{-3}{5}.4=\frac{-12}{5}$
b. $x=\frac{2,1}{0,7}.3=3.3=9$