Question

Qual o número cujo o dobro só. Ado a maia 10 é igual a 40.

Answer 1

$\Large\boxed{\begin{array}{l}\sf n\acute umero:x\\\sf dobro~do~n\acute umero:2x\\\sf dobro~do~n\acute umero~somado~a~10:2x+10\\\sf equac_{\!\!,}\tilde ao: 2x+10=40\\\underline{\rm soluc_{\!\!,}\tilde ao:}\\\sf 2x+10=40\\\sf 2x=40-10\\\sf 2x=30\\\sf x=\dfrac{30}{2}\\\\\sf x=15\end{array}}$