Question

Calcule x na proporção a seguir.



a) 9
b)15
c)5
d)4
e)3

Answer 1

$\large\boxed{\begin{array}{lr} \frac{x + 3}{12 + x} = \frac{2}{3} \\ \\ \frac{x + 3}{12 + x} = \frac{2}{3} \cancel{ = } - 12 \\ \\ 3(x + 3) = 2(12 + x) \\ 3x + 9 = 24 + 2x \\ 3x - 2x = 24 - 9 \\ x = 15,x \cancel{ = } - 12 \\ \boxed{x = 15} \\ \\ \boxed{ \boxed{ \boxed{ \huge\blue{Alternativa \: (B) \: 15}}}}\end{array}}$