Question

Atividade 1.
1 - Dada a proporção
$\frac{x - 7}{10} = \frac{1}{5}$
, o valor de x é:
[A] 3 [B] 6 [C]9 [D] 12 [E] 15.​

Answer 1

$\sf\: \frac{x - 7}{10} = \frac{1}{5} \\ \\ \\ \sf\: \frac{5(x - 7)}{10} = 1 \\ \\ \\ \sf\: 5(x - 7) = 1 \cdot10 \\ \\ \\ \sf\: \frac{5(x - 7) }{5} = 10\\ \\ \\ \sf\: \sf\: x - 7 = 2 \\ \\ \\ \sf\: x = 2 + 7 \\ \\ \\ \boxed{\sf x = 9}$

Att: Nerd1990