Paano nakatutulong sa matalinong pagdedesisyon ng mga konsepto ng trade-off, opportunity cost, at marginal thinking?

How did the united states obtained the purchase of floridia to extand its frontiers to the pacific ocean

Which 19th century technological advancement would best allow farmers along the mississippi river in iowa to quickly transport their crops to buyers in louisiana?

Who was at the top of the feudal system hierarchy