good explanations, formula, graphs , definitions used etc

Q4. What is the sum of the first 12 terms of the following series (rounded to the nearest 10 000) i . 100 000, 85 000, 70 000, 55 000, ... ii. 100 000, 75 000, 56 250, 42 187.5, ...0.6. Suppose that the demand for apartments in a certain area is Qd = 100 2F and the supply is Q5 = 20 + 3P. The market is initially in a competitive equilibrium but the local government is considering imposing a maximum rent (i.e. rent control) at one ofthe two following price points: For each of these two prices, you have been asked to forecast whether the rent ceiling will cause a state of excess supply (ES) excess demand (ED), or both ES 8: ED, or neither ES nor ED