What are the boundaries called that seperate streams in adjacent drainage basins

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

What volcanoes form on a divergent plate margin

Sarah is making a scale drawing of a painting that is 48inches wide by 120 inches high her paper is 12 inches wide and 24 inches tall she decides to use a scale 1 inches equals 4 inches is this a reasonable scale