Assume that in an economy the real interest rate equals r=0.05, the rate of growth of real GDP equals y = 0.03, and the primary deficit-to-GDP ratio equals d=0.03 and is expected to remain constant. a) Write the equation for the dynamics of debt-to-GDP ratio and show the dynamics in a graph. In the case the debt stabilizes, calculate the equilibrium level of debt (as % of GDP). b) What should be the level of the real interest rate (r), to stabilize debt-to-GDP at 150% without change in the primary deficit? Present this situation in a graph.