Question

O valor de x na proporção 4 12 = 21, é:

A) 3;

B) 5;

C) 7;

D) 9;

E) 11;
​

Answer 1

$\frac{4}{12} = \frac{x}{21}$

$12.x = 4 . 21$

$12x = 84$

$x = \frac{84}{12}$

$x = 7$