Answer:
Therefore, we conclude that 480 millions workers are in the labor force.
Explanation:
We know that the number in the working-age population is 500 million, and the unemployment rate is 4%.
We calculate how many workers are in the labor force.
We conclude that 100% - 4% = 96% workers are in the labor force.
We have the following proportion:

Therefore, we conclude that 480 millions workers are in the labor force.