1. Problem: When $y$ varies directly as $x$, and $y=21$ when $x=16$, find $y$ when $x=8$. 2. Formula: Direct variation means $y=kx$ where $k$ is a constant. 3. Find $k$ using given values: $$21 = k \times 16 \implies k = \frac{21}{16}$$ 4. Find $y$ when $x=8$: $$y = k \times 8 = \frac{21}{16} \times 8 = \frac{21 \times 8}{16} = \frac{168}{16} = 10.5$$ Answer: $y=10.5$ when $x=8$. This shows how $y$ changes proportionally with $x$ in direct variation. q_count is 1 because only the first problem is solved as per instructions.