If demand is represented by Qd = 50 -.5P +.005I where I is income and I=$50,000

If demand is represented by Qd = 50 -.5P +.005I where I is income and I=$50,000 and supply is represented by Qs = 100 +.4P - 2W where W is wages and W=$15.00. 
a. Compute the equilibrium price and quantity where wages=W=$15.00.
b. Compute the equilibrium price and quantity if income falls to I=$40,000? 
c. Plot the demand and supply for the two income level. In the graph, mark all values that fully identify the curve.