Question

Nas figuras, a // b // c, calcule o valor de x.

Answer 1

Resposta:

x=7

Explicação passo-a-passo:

$\frac{4}{12} =\frac{x}{21} \\\\12.x=4.21\\\\12.x=84\\\\x=\frac{84}{12} \\\\x=7$