Question

encontre o valor do numero desconhecido
4/6=12/x
0,3/0,5=x1,5
6/x=9/12
3/4=5x/20
x+5=x1

Answer 1

Simples, basta multiplicar cruzado;

$\dfrac{4}{6} = \dfrac{12}{x} \to~~ 4x=6.12\to~~4x=72\to~~x= \dfrac{72}{4} \to~~\boxed{x=18}\\\\\\ \dfrac{0,3}{0,5} = \dfrac{x}{1,5} \to~~0,5x=0,3.1,5\to~~0,5x=0,45\to~~x= \dfrac{0,45}{0,5} \to\\ \boxed{x=0,9}\\\\\\ \dfrac{6}{x} = \dfrac{9}{12} \to~~ 9x=72\to~~x= \dfrac{72}{9}\to~~\boxed{x=8}$



$\dfrac{3}{4} = \dfrac{5x}{20} \to~~ 4.5x=3.20\to~~20x=60\to~~x= \dfrac{60}{20}\to~~\boxed{x=3} \\\\\\ x+5=x\to~~x-x=-5\to~~0x=-5\to~~~~Equa\c c\~ao~~Impossi\´vel.$