PROOF WITHOUT WORDS: $a, b, c, d>0$; $ \frac{a}{b}=\frac{c}{d} \Rightarrow \frac{a}{b}=\frac{c}{d}=\frac{s a+t c}{s b+t d} $. Far East Journal of Mathematical Education, [S. l.], v. 26, n. 2, p. 71–77, 2024. DOI: 10.17654/0973563124008. Disponível em: https://pphmjopenaccess.com/fejme/article/view/2033. Acesso em: 5 jan. 2026.