In one day, Sue can change the oil on 20 cars or change the tires on 20 cars. In one day, Fred can change the oil on 20 cars or change the tires on 10 cars. Sue and Fred can gain from trade if Sue changes the ________ and Fred changes the ________

With regard to education of freed slaves after the Civil War (1861–1865),

(a) there was a rapid rise of literacy. (b) Southern public schools were "separate, but equal." (c) most had received no education under slavery and were illiterate. (d) all of the above are true.

"Scarcity implies that some way of rationing goods must be found." Explain what this statement means. How is this rationing done?

What will be an ideal response?