Question

15/4=30/x proporções​

Answer 1

$\Large\displaystyle\text{ \begin{gathered} \sf{\frac{15}{4}=\frac{30}{x} } \end{gathered} }$

$\Large\displaystyle\begin{gathered} \sf{15 x=30\cdot4} \end{gathered}$

$\Large\displaystyle\begin{gathered} \sf{15x=120 } \end{gathered}$

$\Large\displaystyle\text{ \begin{gathered} \boxed{\boxed{\sf{ x=8}}} \end{gathered} }$