Final answer:
Approximately 22% of US adults meet the physical activity guidelines for both aerobic and muscle-strengthening activity.
Step-by-step explanation:
Approximately **22%** of US adults meet the physical activity guidelines for **both aerobic and muscle-strengthening activity**. According to the **2018 Physical Activity Guidelines for Americans**, adults should aim for at least 150 minutes (2.5 hours) to 300 minutes (5 hours) of moderate-intensity aerobic activity per week, or 75 minutes (1 hour and 15 minutes) to 150 minutes (2 hours and 30 minutes) of vigorous-intensity aerobic activity per week, along with muscle-strengthening activities on 2 or more days per week.