Calculating Commuting Residents in a City

In a certain city, it is observed that 40% of the residents commute using public transportation. Among those who do not use public transportation, 25% carpool to work, while the remaining commute alone. If the city has a total population of 100,000 residents, how many residents primarily commute alone?

Let’s define:

• Public Transportation Users: $PT = 40\% \times 100,000$
• Non-Public Transportation Users: $NPT = 100,000 - PT$
• Carpool Users: $CP = 25\% \times NPT$
• Residents Commuting Alone: $A = NPT - CP$