Question

in a small town, 10 residents move to new cities each year for 3 years. the equation below is written to represent the situation

$$ ( - 10 ) cdot 3 = - 30 $$

which description best explains the meaning of - 30 in the equation?

a - 30 residents leave the town.

b there are - 30 residents in the town.

c the change in the number of residents per year is - 30.

d the total change in the number of residents in the town due to people moving away is - 30.

Explanation:

• Option A: The number of residents leaving per year is 10, not - 30.
• Option B: The number of residents in a town cannot be negative in a practical sense.
• Option C: The change per year is - 10 (10 residents leaving per year), not - 30.
• Option D: Since 10 residents leave each year for 3 years, the total change is \((-10)\times3=-30\), which represents the total number of residents who left (a decrease, hence negative) over 3 years.

Answer:

D. The total change in the number of residents in the town due to people moving away is - 30.