156÷52(90+63)90×55÷220-6000=
please help me

Uncle tom's cabin started out as a series of articles printed in the national era, a newspaper.

What evidence supports geological processes changing the surface of the earth? cutting down forests creates a decrease of habitats. tectonic plates uplift the rocky crust of earth to form mountains. competition in ecosystems creates a decrease in diversity. pollution runoff contaminates a lake.

What are cutting "steps" or terraces