If AB = 4x + 7 BC = 13x and AC = 20x + 50 what is AB

Using complete sentences, describe the central economic problem facing all humans. why does this require people to make choices? how can this result in opportunity costs?

What is the northern most national park in the world

1. in 1492, spain expelled after being under their rule for centuries. a. the portuguese b. the basques c. the castilians d. the moors 2. an important cultural center during the renaissance was the city of a. milan b. bologna c. florence d. naples 3. what is the connection between the minoan civilization and a volcanic eruption on thera? a. the earthquake happened a century before the collapse of the civilization. b. the earthquake created a graben. c. the earthquake caused the collapse of the civilization. d. the earthquake caused a volcanic eruption. 4. throughout history, other cultures influenced greece through a. military conquest b. shared ideals c. trade agreements 5. geographically, spain is isolated from the rest of europe by a. portugal b. the atlantic ocean c. the pyrenees mountains d. narrow coastal plains 6. most of central spain is known as the meseta, which is the spanish word for a. mountains b. plateau c. peninsula d. plains 7. for the people of ancient greece, the  iliad, and the  odyssey  a. copied western ideals b. were not popular c. presented community standards d. were children’s poems\ 8. western cultures got many of their ideas about from ancient greece. a. warfare b. democracy c. education d. agriculture 9. how is greece’s natural vegetation similar to that of other mediterranean countries? a. it has been damaged by forest fires. b. it is mainly deciduous forests. c. it grows rapidly in the wet climate. d. it has been reduced to scrub vegetation by overgrazing. 10. what is the most productive agricultural area in italy? a. the alps b. the po valley c. southern italy d. the apennines 11. many factories in northern italy use for energy. a. coal b. hydroelectricity c. nuclear energy d. natural gas 12. what major landform covers much of italy? a. the apennines b. the po river valley c. the alps