please do for an example do not understand

Question 4. Suppose Megabox is a new case designed for smartphones. We know its demand curve and supply curve as below. Here the units of P and Q are, P: $/case, Q: thousand cases. . Demand function: Qa = 100 - 2 * P . Supply function: Qs = -20 +4 * P (1) How much is consumer surplus (CS) when Megabox is priced at $35 in the market? (2) How much is consumer surplus (CS) when price the case drops to $25? (3) How much is consumer surplus (CS) at market equilibrium price of Megabox? (4) How much is producer surplus (PS) and total surplus (TS) at market equilibrium