The ratio of flour to sugar is $3:2$. To go from 3 cups of flour to 12 cups of flour, multiply by 4. To keep the ratio the same, also multiply the sugar amount by 4: $2\times 4=8$. So 8 cups of sugar are needed.

The original actual distance is found from the scale: $2.5\times 8=20$ miles. After the road is built, the actual distance becomes $20-6=14$ miles. Using the same scale of $1$ inch for every $8$ miles, the new map distance is $\frac{14}{8}=1.75$ inches. Therefore, the correct answer is $1.75$.

The ratio of concentrate to water is $2:5$. That means for every $2$ cups of concentrate, there are $5$ cups of water. To find the amount of water for $c$ cups of concentrate, multiply $c$ by the ratio $\frac{5}{2}$:

So the correct expression is $\frac{5}{2}c$.

The rate in blocks per minute is the slope of the line. Using the two points,

So the person walks $3$ blocks per minute.

The ratio of student tickets to adult tickets is $3:2$. That means there are $3+2=5$ total equal parts in the ratio. Since 40 tickets were sold altogether, each part represents $\frac{40}{5}=8$ tickets. Adult tickets correspond to 2 parts, so the number of adult tickets is $2\cdot 8=16$.