MathNet 2019-part-07 — 184 problems (EN–VI) Question 151

Let $a$ and $b$ be positive whole numbers such that $\frac{4.5}{11} \lt \frac{a}{b} \lt \frac{5}{11}$. Find the fraction $\frac{a}{b}$ for which the sum $a+b$ is as small as possible. Justify your answer.