PROOF WITHOUT WORDS: $\frac{a}{b}=\frac{c}{d} \Rightarrow \frac{a}{b}=\frac{c}{d}=\frac{a \pm c}{b \pm d}$ IN THE RANGE OF NATURAL NUMBERS. FEJME [Internet]. 2022 Jun. 15 [cited 2026 Jan. 5];22:29-32. Available from: https://pphmjopenaccess.com/fejme/article/view/666