Question

Preciso de ajuda, por-favor !

Answer 1

Resposta:

a)

$\dfrac{x-10}{50}=\dfrac{2}{5}\\ \\ multiplica~~cruzado\\ \\ \\ 5.(x-10)=100\\ \\ 5x-50=100\\ \\ 5x=100+50\\ \\ 5x=150\\ \\ x=150\div5\\ \\\boxed{ x=30}}$

b)

$\dfrac{2}{4}=\dfrac{20}{x+10}\\ \\ 2.(x+10)=80\\ \\ 2x+20=80\\ \\ 2x=80-20\\ \\ 2x=60\\ \\ x=60\div2\\ \\ \boxed{x=30}$

c)

$\dfrac{10}{x-10}=\dfrac{3}{6}\\ \\ 3(x-10)=60\\ \\ 3x-30=60\\ \\ 3x=60+30\\ \\ 3x=90\\ \\ x=90\div3\\ \\\boxed{ x=30}$

d)

$\dfrac{2}{8}=\dfrac{20}{x+10}\\ \\ 2.(x+10)=160\\ \\ 2x+20=160\\ \\ 2x=160-20\\ \\ 2x=140\\ \\ x=140\div2\\ \\\boxed{ x=70}$