Question

Quem, souber a resposta dessa coloque !​

Answer 1

❑ •Teorema de Tales

$\frac{4}{12} = \frac{x}{21} \\ \\ 12x = 84 \\ x = \frac{84}{12} \\ \\ \boxed{\boxed{\green{x = 7}}}$

✿ ~Sah