The correct graph is the second one from the first row.
Step-by-step explanation:
Since his initial income was $20,000 per year, then the graph line must cross the "y" axis in that value. Since his average increase in pay on those eight years was $4,000, then for each one year step on the "x" axis the function must increase approximately "4,000" on the "y" axis. The only graph that follow this rule is the second graph on the first row. Since it starts at 20 on the "y" axis and it doubles to "40" only after 5 years, therefore increasing 4 per year.
