Question

Complete this proportion $\frac{7}{21}=\frac{4}{?}$

Answer 1

Let the missing number be $x$

$\frac{7}{21}=\frac{4}{x}$

$\Rightarrow \frac{1}{3}=\frac{4}{x}$

$\Rightarrow x=4\times 3=12$

$\therefore x=12$