“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, vol. 26, no. 2, Aug. 2024, pp. 71-77, https://doi.org/10.17654/0973563124008.