I need an economics expert. The following is an international trade area of economics. Please help me fully understand the following graph. I have no idea why there is a vertical line, why there are two horizontal lines, why RD moved to RD' and why this RS curve looks so different. Fig. 3-3: World Relative Supply and Demand Relative price of cheese, PJPW aiclaw RS (2 in our example) RD alc/alw (1/2 in our example) RD' Q L/aLc Relative quantity L*/aLW Qc + QC of cheese, Qw +Qw