Final answer:
The total number of workers in the economy is found by adding the 10 million part-time workers to the 90 million full-time workers, which equals 100 million workers in total.
Step-by-step explanation:
To find the total number of workers in the economy, you simply add the number of part-time workers to the number of full-time workers. Given there are 10 million part-time workers and 90 million full-time workers:
Total workers = Part-time workers + Full-time workers
Total workers = 10 million + 90 million
Total workers = 100 million
Therefore, the total number of workers in the economy is 100 million.