Find the distance between these two lines y=-1/3x+7 and y=-1/3x-3

In 1915 the german geologist and meteorologist alfred wegener first proposed the theory of continental drift, which states that parts of the earth's crust slowly drift atop a liquid core. the fossil record supports and gives credibility to the theories of continental drift and plate tectonics.

What causes the cyclical changes in the appearance of the moon?

The primary agent of contact metamorphism is