Question

Tìm x biết :

7/x = 3/12

Answer 1

\(\frac{7}{x}=\frac{3}{12}\)

\(\Leftrightarrow\) 7.12=3\(x\)

\(\Leftrightarrow\) 84=3x

\(\Leftrightarrow\)x=84:3

\(\Leftrightarrow\) x=28

Vậy x=28

Answer 2

Áp dụng tính chất tỉ lệ thức ta có :

\(\frac{7}{x}=\frac{3}{12}\Rightarrow7.12=3x\)

\(\Rightarrow3x=84\)

\(\Rightarrow x=\frac{84}{3}\)

\(\Rightarrow x=28\)

Vậy x = 28

Answer 3

\(\frac{7}{x}=\frac{3}{12}\) => \(7.12=3x\) => \(84=3x\) => \(x=\frac{84}{3}=28\)

Answer 4

\(\frac{7}{x}=\frac{3}{12}\)

\(\frac{7}{x}=\frac{1}{4}\)

\(\frac{1}{4}=\frac{1\times7}{4\times7}=\frac{7}{28}\)

\(\Rightarrow x=28\)

Answer 5

\(\frac{7}{x}=\frac{3}{12}\Rightarrow3x=7.12\Rightarrow3x=84\Rightarrow x=84:3=28\)

vậy x=28