In the image, you are given a problem that involves a percentage of families owning pets. The total number of families is 400, and 35% of them own pets. Let's break down how to solve both parts:

(a) Double Number Line:

• The top number line will represent the percentage of families (from 0% to 100%).
• The bottom number line will represent the number of families (from 0 to 400).
• You will need to align the percentage values with the corresponding number of families. For instance:
  • At 0% on the top line, you would have 0 families on the bottom line.
  • At 35% on the top line, you need to calculate how many families that corresponds to on the bottom line.

To calculate: $\text{Families with pets} = 35\% \times 400 = \frac{35}{100} \times 400 = 140 \text{ families}$

Thus, on the double number line:

• 35% corresponds to 140 families.

(b) How many families own pets? From part (a), we've already calculated that 140 families own pets.

Would you like further explanation or details?

Here are five related questions:

1. How would the double number line change if 50% of families owned pets?
2. What is the relationship between percentages and fractions?
3. How can the number of families be calculated if the percentage changes to 25%?
4. What method could be used if the total number of families was unknown?
5. How would the problem be solved using a ratio instead of a percentage?

Tip: Percentages can always be converted into fractions or decimals to simplify the calculation.