The cost of attending a 4-year college can be calculated by summing up the tuition, textbooks, and room and board expenses for each year:
Tuition cost for 4 years: $12,000/year * 4 years = $48,000
Textbook cost for 4 years: $3,000/year * 4 years = $12,000
Room and board cost for 4 years: $10,000/year * 4 years = $40,000
Total cost of attending a 4-year college: $48,000 + $12,000 + $40,000 = $100,000
Additionally, we need to consider the opportunity cost of attending college. The opportunity cost is the value of the next best alternative foregone, which in this case is the salary you would have earned if you had taken the job instead of going to college.
Opportunity cost of attending college: $15,000/year * 4 years = $60,000
Therefore, the total cost of attending a 4-year college, including the opportunity cost, is $100,000 + $60,000 = $160,000.