Can you help me understand this answer? What is the supply? Is it the income?

1. Joshua's income increases, while federal taxes increase; therefore, please illustrate by constructing a supply and demand graph, the direction in which the curves will shift and state the new equilibrium price and quantity; for example, state whether price and quantity increased, decreased, or are indeterminate. Please explain your rationale based on the determinants of demand and supply.

Price Quantity