Javob va yechimni ko‘rish
Javob: $\frac{11}{12}$
Kasrlarni qo‘shish va ayirish uchun avvalo ularning umumiy (bir xil) maxrajini topamiz. $4$, $6$ va $3$ sonlarining eng kichik umumiy bo‘luvchisi $12$ ga teng, shuning uchun barcha kasrlarni $12$ ga teng bo‘lishi kerak:
$$\frac{3}{4}=\frac{3\cdot3}{4\cdot3}=\frac{9}{12},\qquad
\frac{5}{6}=\frac{5\cdot2}{6\cdot2}=\frac{10}{12},\qquad
\frac{2}{3}=\frac{2\cdot4}{3\cdot4}=\frac{8}{12}.$$
Endi bu kasrlarni birga hisoblaymiz:
$$\frac{9}{12}+\frac{10}{12}-\frac{8}{12}= \frac{9+10-8}{12}= \frac{11}{12}.$$
Demak, ifoda soddalashtirilganda $\displaystyle \frac{11}{12}$ ga teng bo‘ladi, ya’ni to‘g‘ri javob C.