How old am i if 200 reduced by 2 times my age is 18

Plzz on what physical process is responsible for the creation of volcanoes, earthquakes and ocean trenches at the plate margins?

Afarmer who is grown corn for the past five years notices in the sixth year that the his harvest is significantly smaller, despite an increase in labor on the farm. the following year, the harvest continue to decline. which of the following explanations most plausibly accounts for the reduction in corn yield? a) soil degradation b) desalinization c) better irrigationd) terracing

How has plate tectonics affected the climate of south america?