What is meant here is that James will lose the income from his current job, namely $42,000/year times 2 years = $84,000
The cost of his education will be $28,000/year times 2 years = $56,000
The sum of the lost income and two years of education expense will be $140,000
So, $140,000 ÷ $56,000/year = 2.5 years
option b