Solution:

Set up proportion: $\frac{3 \text{ pounds}}{\$4.50} = \frac{7 \text{ pounds}}{x}$

Cross multiply: $3x = 4.50 \times 7$ $3x = 31.50$ $x = 10.50$

Answer: \10.50$

Solution:

Set up proportion: $\frac{2 \text{ inches}}{50 \text{ miles}} = \frac{7 \text{ inches}}{x \text{ miles}}$

Cross multiply: $2x = 50 \times 7$ $2x = 350$ $x = 175$

Answer: 175 miles