1. The problem is to find the missing numerator $x$ in the equation $$8 \times \frac{x}{6} = \frac{20}{3}$$. 2. The formula used here is to solve for $x$ in a proportion or equation involving fractions. 3. Start by isolating $x$: $$8 \times \frac{x}{6} = \frac{20}{3}$$ Multiply both sides by 6 to eliminate the denominator on the left: $$8x = \frac{20}{3} \times 6$$ 4. Simplify the right side: $$8x = \frac{20 \times 6}{3} = \frac{120}{3} = 40$$ 5. Now solve for $x$ by dividing both sides by 8: $$x = \frac{40}{8} = 5$$ 6. Therefore, the missing numerator is $5$. This means the original equation is: $$8 \times \frac{5}{6} = \frac{20}{3}$$ which is true.