12. Ko‘paytiring. a) \(\frac{4}{5}\times35\); b) \(\frac{8}{9}\times81\); c) \(\frac{2}{3}\times20\); d) \(\frac{4}{7}\times45\); e) \(\frac{5}{6}\times34\); f) \(\frac{7}{8}\times28\).

Butun sonni kasrga ko‘paytirish uchun sonni kasrning suratiga ko‘paytirib, maxrajiga bo‘lamiz.

1. а) \(\frac{4}{5}\times35=4\times(35:5)=4\times7=28\).
2. б) \(\frac{8}{9}\times81=8\times(81:9)=8\times9=72\).
3. с) \(\frac{2}{3}\times20=2\times(20:3)=\frac{40}{3}=13\frac{1}{3}\).
4. d) \(\frac{4}{7}\times45=\frac{4\times45}{7}=\frac{180}{7}=25\frac{5}{7}\).
5. e) \(\frac{5}{6}\times34=\frac{5\times34}{6}=\frac{170}{6}=\frac{85}{3}=28\frac{1}{3}\).
6. f) \(\frac{7}{8}\times28=7\times(28:8)=\frac{196}{8}=\frac{49}{2}=24\frac{1}{2}\).

Javob: а) 28; б) 72; с) 13⅓; d) 25⅚?